| Message ID | 20250303084724.6490-1-kanchana.p.sridhar@intel.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | zswap IAA compress batching | expand |
This commit adds a get_batch_size() interface to: struct acomp_alg struct crypto_acomp A crypto_acomp compression algorithm that supports batching of compressions and decompressions must register and provide an implementation for this API, so that higher level modules such as zswap and zram can allocate resources for submitting multiple compress/decompress jobs that can be batched. In addition, the compression algorithm must register itself to use request chaining (cra_flags |= CRYPTO_ALG_REQ_CHAIN). A new helper function acomp_has_async_batching() can be invoked to query if a crypto_acomp has registered this API. Further, the newly added crypto_acomp API "crypto_acomp_batch_size()" is provided for use by higher level modules like zswap and zram. crypto_acomp_batch_size() returns 1 if the acomp has not provided an implementation for get_batch_size(). For instance, zswap can call crypto_acomp_batch_size() to get the maximum batch-size supported by the compressor. Based on this, zswap can use the minimum of any zswap-specific upper limits for batch-size and the compressor's max batch-size, to allocate batching resources. Further, the way that zswap can avail of the compressor's batching capability is by using request chaining to create a list requests chained to a head request. zswap can call crypto_acomp_compress() or crypto_acomp_decompress() with the head request in the chain for processing the chain as a batch. The call into crypto for compress/decompress will thus remain the same from zswap's perspective for both, batching and sequential compressions/decompressions
IAA Compression Batching with crypto_acomp Request Chaining: ============================================================ This patch-series introduces the use of the Intel Analytics Accelerator (IAA) for parallel batch compression of pages in large folios to improve zswap swapout latency. It does this by first creating a generic batching framework in crypto_acomp using request chaining, followed by invoking request chaining API to compress/decompress a batch in the iaa_crypto driver. From zswap's perspective, the most significant changes are: 1) A unified zswap_batch_compress() API is added to compress multiple pages. If the compressor has multiple acomp requests, i.e., internally supports batching, a request chain is created and crypto_acomp_compress() is called with the head request in the chain. In the iaa_crypto driver, the request chain is batch compressed in parallel. If the compressor can only compress one page at a time, each page is compressed sequentially. In both cases, the calls to crypto are exactly the same: crypto_wait_req(crypto_acomp_compress(acomp_ctx->reqs[0]), &acomp_ctx->wait); Many thanks to Yosry for this suggestion, because it is an essential component of unifying common code paths between sequential/batching compressions. 2) zswap_compress() has been deleted, since we call zswap_batch_compress() in all cases. 3) A new zswap_store_pages() is added, that stores multiple pages in a folio in a range of indices. This is an extension of the earlier zswap_store_page(), except it operates on a batch of pages. 4) A new zswap_store_folio() is added, that stores all pages in a folio by calling zswap_store_pages(). If the compressor supports batching, i.e., has multiple acomp requests, the folio will be compressed in batches of "acomp_ctx->nr_reqs" using request chaining. If the compressor has only one acomp request, the folio will be compressed in batches of ZSWAP_MAX_BATCH_SIZE pages, where each page in the batch is compressed sequentially. 5) A simplification of the acomp_ctx resources allocation/deletion vis-a-vis CPU hot[un]plug. v8 of this patch-series proposes that these resources are not destroyed during CPU offlining, rather have a lifespan that tracks the zswap_pool's: from pool creation to pool deletion. This is in response to Yosry's comments in v6 with regards to exploring mutex locking options in zswap_cpu_comp_prepare(). Improvements seen with v8's IAA compress batching with request chaining vs. IAA sequential: usemem30 with 64K folios: 70% higher throughput 32% lower elapsed time 32% lower sys time usemem30 with 2M folios: 68% higher throughput 24% lower elapsed time 24% lower sys time Kernel compilation allmod config with 64K folios: 8.4% lower sys time There are no regressions seen with zstd with either usemem30 or kernel compilation allmod config. In v8, there are only very minor changes wrt v7 for patches 1 through 13. The only major change is in patch 14. The patch-series is organized as follows: 1) crypto acomp & iaa_crypto driver enablers for batching: Relevant patches are tagged with "crypto:" in the subject: Patch 1) Adds new acomp request chaining framework and interface based on Herbert Xu's ahash reference implementation in "[PATCH 2/6] crypto: hash - Add request chaining API" [1]. acomp algorithms can use request chaining through these interfaces: Setup the request chain: acomp_reqchain_init() acomp_request_chain() Process the request chain: acomp_do_req_chain(): synchronously (sequentially) acomp_do_async_req_chain(): asynchronously using submit/poll ops (in parallel) Query if a request has a chain of requests that need to be processed with it, as a batch: acomp_is_reqchain() Patch 2) Adds acomp_alg/crypto_acomp interfaces for get_batch_size(), that swap modules can invoke using the new crypto_acomp_batch_size() API, to get the maximum batch size supported by a compressor before allocating batching resources. Patch 3) New CRYPTO_ACOMP_REQ_POLL acomp_req flag to act as a gate for async poll mode in iaa_crypto. Patch 4) iaa-crypto driver implementations for async and sync compress and decompress batching using request chaining. The driver's compress() and decompress() interface implementations will query acomp_is_reqchain() to do batched vs. sequential compression/decompression. If the iaa_crypto driver is set up for 'async' sync_mode, these batching implementations deploy the asynchronous request chaining framework provided via acomp_do_async_req_chain() in patch 1. 'async' is the recommended mode for realizing the benefits of IAA parallelism. If iaa_crypto is set up for 'sync' sync_mode, the synchronous version of the request chaining API is used, i.e., acomp_do_req_chain() - this will process the chain in series. The "iaa_acomp_fixed_deflate" algorithm opts in to request chaining with CRYPTO_ALG_REQ_CHAIN, and registers the get_batch_size() interface, which returns the IAA_CRYPTO_MAX_BATCH_SIZE constant that iaa_crypto defines currently as 8U for IAA compression algorithms (iaa_crypto can change this if needed as we optimize our batching algorithm). Patch 5) Modifies the default iaa_crypto driver mode to async, now that iaa_crypto provides a truly async mode that gives significantly better latency than sync mode for the batching use case. Patch 6) Disables verify_compress by default, to facilitate users to run IAA easily for comparison with software compressors. Patch 7) Reorganizes the iaa_crypto driver code into logically related sections and avoids forward declarations, in order to facilitate Patch 8. This patch makes no functional changes. Patch 8) Makes a major infrastructure change in the iaa_crypto driver, to map IAA devices/work-queues to cores based on packages instead of NUMA nodes. This doesn't impact performance on the Sapphire Rapids system used for performance testing. However, this change fixes functional problems we found on Granite Rapids in internal validation, where the number of NUMA nodes is greater than the number of packages, which was resulting in over-utilization of some IAA devices and non-usage of other IAA devices as per the current NUMA based mapping infrastructure. This patch also eliminates duplication of device wqs in per-cpu wq_tables, thereby saving 140MiB on a 384 cores Granite Rapids server with 8 IAAs. Submitting this change now so that it can go through code reviews before it can be merged. Patch 9) Builds upon the new infrastructure for mapping IAAs to cores based on packages, and enables configuring a "global_wq" per IAA, which can be used as a global resource for compress jobs for the package. If the user configures 2WQs per IAA device, the driver will distribute compress jobs from all cores on the package to the "global_wqs" of all the IAA devices on that package, in a round-robin manner. This can be used to improve compression throughput for workloads that see a lot of swapout activity. Patch 10) Makes an important change to iaa_crypto driver's descriptor allocation, from blocking to non-blocking with retries/timeouts and mitigations in case of timeouts during compress/decompress ops. This prevents tasks getting blocked indefinitely, which was observed when testing 30 cores running workloads, with only 1 IAA enabled on Sapphire Rapids (out of 4). These timeouts are typically only encountered, and associated mitigations exercised, only in configurations with 1 IAA device shared by 30+ cores. Patch 11) Fixes a bug with the "deflate_generic_tfm" global being accessed without locks in the software decomp fallback code. 2) zswap modifications to enable compress batching in zswap_store() of large folios (including pmd-mappable folios): Patch 12) Simplifies acomp_ctx resources to have a lifespan from pool creation to pool deletion, persisting through CPU hot[un]plugs after initial allocation. Patch 13) Defines a zswap-specific ZSWAP_MAX_BATCH_SIZE (currently set as 8U) to denote the maximum number of acomp_ctx batching resources. Further, the "struct crypto_acomp_ctx" is modified to contain a configurable number of acomp_reqs and buffers. The cpu hotplug onlining code will allocate up to ZSWAP_MAX_BATCH_SIZE requests/buffers in the per-cpu acomp_ctx, thereby limiting the memory usage in zswap, and ensuring that non-batching compressors incur no memory penalty except for minimal overhead. Patch 14) Restructures & simplifies zswap_store() to make it amenable for batching. Moves the loop over the folio's pages to a new zswap_store_folio(), which in turn calls a new zswap_store_pages() with a range of indices in the folio to be stored. zswap_store_pages() calls the new zswap_batch_compress() to use compression batching with request chaining to compress multiple pages in one shot (in parallel in IAA), or to sequentially compress each page in the batch. zstd performance is on par with mm-unstable. We see impressive throughput/performance improvements with IAA batching vs. no-batching. With v8 of this patch series, the IAA compress batching feature will be enabled seamlessly on Intel platforms that have IAA by selecting 'deflate-iaa' as the zswap compressor, and using the iaa_crypto 'async' sync_mode driver attribute. [1]: https://lore.kernel.org/linux-crypto/677614fbdc70b31df2e26483c8d2cd1510c8af91.1730021644.git.herbert@gondor.apana.org.au/ System setup for testing: ========================= Testing of this patch-series was done with mm-unstable as of 2-27-2025, commit d58172d128ac, without and with this patch-series. Data was gathered on an Intel Sapphire Rapids (SPR) server, dual-socket 56 cores per socket, 4 IAA devices per socket, 503 GiB RAM and 525G SSD disk partition swap. Core frequency was fixed at 2500MHz. Other kernel configuration parameters: zswap compressor : zstd, deflate-iaa zswap allocator : zsmalloc vm.page-cluster : 0 IAA "compression verification" is disabled and IAA is run in the async mode (the defaults with this series). I ran experiments with these workloads: 1) usemem 30 processes with these large folios enabled to "always": - 64k - 2048k 2) Kernel compilation allmodconfig with 2G max memory, 32 threads, run in tmpfs with these large folios enabled to "always": - 64k Performance testing (usemem30): =============================== The vm-scalability "usemem" test was run in a cgroup whose memory.high was fixed at 150G. The is no swap limit set for the cgroup. 30 usemem processes were run, each allocating and writing 10G of memory, and sleeping for 10 sec before exiting: usemem --init-time -w -O -b 1 -s 10 -n 30 10g 64K folios: usemem30: deflate-iaa: ================================== ------------------------------------------------------------------------------- mm-unstable-2-27-2025 v8 ------------------------------------------------------------------------------- zswap compressor deflate-iaa deflate-iaa IAA Batching vs. Sequential ------------------------------------------------------------------------------- Total throughput (KB/s) 6,025,001 10,220,686 70% Avg throughput (KB/s) 200,833 340,689 elapsed time (sec) 100.25 68.48 -32% sys time (sec) 2,414.12 1,630.42 -32% ------------------------------------------------------------------------------- memcg_high 912,474 1,007,870 memcg_swap_fail 0 0 zswpout 58,338,296 64,507,786 zswpin 65 69 pswpout 0 0 pswpin 0 0 thp_swpout 0 0 thp_swpout_fallback 0 0 64kB_swpout_fallback 941 125 pgmajfault 2,867 2,943 anon_fault_alloc_64kB 4,924,286 4,923,648 ZSWPOUT-64kB 3,645,190 4,031,585 SWPOUT-64kB 0 0 ------------------------------------------------------------------------------- 2M folios: usemem30: deflate-iaa: ================================= ------------------------------------------------------------------------------- mm-unstable-2-27-2025 v8 ------------------------------------------------------------------------------- zswap compressor deflate-iaa deflate-iaa IAA Batching vs. Sequential ------------------------------------------------------------------------------- Total throughput (KB/s) 6,374,303 10,720,261 68% Avg throughput (KB/s) 212,476 357,342 elapsed time (sec) 87.04 65.80 -24% sys time (sec) 2,012.30 1,522.93 -24% ------------------------------------------------------------------------------- memcg_high 115,418 125,177 memcg_swap_fail 0 0 zswpout 59,471,372 64,509,017 zswpin 10 441 pswpout 0 0 pswpin 0 0 thp_swpout 0 0 thp_swpout_fallback 24 222 pgmajfault 2,784 3,226 anon_fault_alloc_2048kB 153,737 153,733 ZSWPOUT-2048kB 116,131 125,781 SWPOUT-2048kB 0 0 ------------------------------------------------------------------------------- 64K folios: usemem30: zstd: =========================== ------------------------------------------------------------------------------- mm-unstable-2-27-2025 v8 v8 ------------------------------------------------------------------------------- zswap compressor zstd zstd zstd ------------------------------------------------------------------------------- Total throughput (KB/s) 6,920,374 6,935,013 6,924,096 Avg throughput (KB/s) 230,679 231,167 230,803 elapsed time (sec) 94.62 88.77 89.79 sys time (sec) 2,387.50 2,213.12 2,250.91 ------------------------------------------------------------------------------- memcg_high 764,199 763,887 764,378 memcg_swap_fail 0 0 0 zswpout 48,917,234 48,897,180 48,928,700 zswpin 426 422 430 pswpout 0 0 0 pswpin 0 0 0 thp_swpout 0 0 0 thp_swpout_fallback 0 0 0 64kB_swpout_fallback 2,190 2,178 2,231 pgmajfault 3,231 3,210 3,206 anon_fault_alloc_64kB 4,924,864 4,924,556 4,924,192 ZSWPOUT-64kB 3,055,153 3,053,916 3,055,843 SWPOUT-64kB 0 0 0 ------------------------------------------------------------------------------- 2M folios: usemem30: zstd: ========================== ------------------------------------------------------------------------------- mm-unstable-2-27-2025 v8 ------------------------------------------------------------------------------- zswap compressor zstd zstd ------------------------------------------------------------------------------- Total throughput (KB/s) 7,655,965 7,685,827 Avg throughput (KB/s) 255,198 256,194 elapsed time (sec) 86.52 81.10 sys time (sec) 2,030.63 1,886.54 ------------------------------------------------------------------------------- memcg_high 93,106 93,054 memcg_swap_fail 0 0 zswpout 48,091,648 48,054,576 zswpin 0 398 pswpout 0 0 pswpin 0 0 thp_swpout 0 0 thp_swpout_fallback 8 203 pgmajfault 2,794 3,242 anon_fault_alloc_2048kB 153,736 153,742 ZSWPOUT-2048kB 93,921 93,678 SWPOUT-2048kB 0 0 ------------------------------------------------------------------------------- Performance testing (Kernel compilation, allmodconfig): ======================================================= The experiments with kernel compilation test, 32 threads, in tmpfs use the "allmodconfig" that takes ~12 minutes, and has considerable swapout/swapin activity. The cgroup's memory.max is set to 2G. 64K folios: Kernel compilation/allmodconfig: ============================================ -------------------------------------------------------------------------------- mm-unstable v8 mm-unstable v8 -------------------------------------------------------------------------------- zswap compressor deflate-iaa deflate-iaa zstd zstd -------------------------------------------------------------------------------- real_sec 775.83 742.52 769.39 762.85 user_sec 15,659.10 15,644.82 15,666.28 15,636.25 sys_sec 4,209.69 3,856.43 5,277.86 5,242.89 -------------------------------------------------------------------------------- Max_Res_Set_Size_KB 1,871,116 1,873,212 1,873,200 1,871,732 -------------------------------------------------------------------------------- memcg_high 0 0 0 0 memcg_swap_fail 0 0 0 0 zswpout 107,305,181 101,061,420 86,621,912 87,004,261 zswpin 32,418,991 29,825,342 25,337,514 25,530,348 pswpout 272 597 94 86 pswpin 274 519 54 84 thp_swpout 0 0 0 0 thp_swpout_fallback 0 0 0 0 64kB_swpout_fallback 494 0 0 0 pgmajfault 34,577,545 31,830,251 26,892,991 27,111,920 ZSWPOUT-64kB 3,498,796 3,276,189 2,737,544 2,766,736 SWPOUT-64kB 17 36 4 5 -------------------------------------------------------------------------------- With the iaa_crypto driver changes for non-blocking descriptor allocations, no timeouts-with-mitigations were seen in compress/decompress jobs, for all of the above experiments. Summary: ======== The performance testing data with usemem 30 processes and kernel compilation test show 68%-70% throughput gains and 24%-32% sys time reduction (usemem30) and 8.4% sys time reduction (kernel compilation) with zswap_store() large folios using IAA compress batching as compared to IAA sequential. There is no performance regression for zstd/usemem30 and zstd/kernel compilation allmod config, and even a 7.3% sys time reduction for zstd/usemem, most likely due to the performance optimizations implemented in zswap_batch_compress() in patch 14 of v8, such as likely/unlikely compiler directives to minimize branch mis-predicts, and the use of prefetchw of the zswap entry before it is written. We can expect to see even more significant performance and throughput improvements if we use the parallelism offered by IAA to do reclaim batching of 4K/large folios (really any-order folios), and using the zswap_store() high throughput compression to batch-compress pages comprising these folios, not just batching within large folios. This is the reclaim batching patch 13 in v1, which will be submitted in a separate patch-series. Our internal validation of IAA compress/decompress batching in highly contended Sapphire Rapids server setups with workloads running on 72 cores for ~25 minutes under stringent memory limit constraints have shown up to 50% reduction in sys time and 21.3% more memory savings with IAA, as compared to zstd, for same performance. IAA batching demonstrates more than 2X the memory savings obtained by zstd for same performance. Changes since v7: ================= 1) Rebased to mm-unstable as of 3-3-2025, commit 5f089a9aa987. 2) Changed the acomp_ctx->nr_reqs to be u8 since ZSWAP_MAX_BATCH_SIZE is defined as 8U, for saving memory in this per-cpu structure. 3) Fixed a typo in code comments in acomp_ctx_get_cpu_lock(): acomp_ctx->initialized to acomp_ctx->__online. 4) Incorporated suggestions from Yosry, Chengming, Nhat and Johannes, thanks to all! a) zswap_batch_compress() replaces zswap_compress(). Thanks Yosry for this suggestion! b) Process the folio in sub-batches of ZSWAP_MAX_BATCH_SIZE, regardless of whether or not the compressor supports batching. This gets rid of the kmalloc(entries), and allows us to allocate an array of ZSWAP_MAX_BATCH_SIZE entries on the stack. This is implemented in zswap_store_pages(). c) Use of a common structure and code paths for compressing a folio in batches, either as a request chain (in parallel in IAA hardware) or sequentially. No code duplication since zswap_compress() has been replaced with zswap_batch_compress(), simplifying maintainability. 5) A key difference between compressors that support batching and those that do not, is that for the latter, the acomp_ctx mutex is locked/unlocked per ZSWAP_MAX_BATCH_SIZE batch, so that decompressions to handle page-faults can make progress. This fixes the zstd kernel compilation regression seen in v7. For compressors that support batching, for e.g. IAA, the mutex is locked/released once for storing the folio. 6) Used likely/unlikely compiler directives and prefetchw to restore performance with the common code paths. Changes since v6: ================= 1) Rebased to mm-unstable as of 2-27-2025, commit d58172d128ac. 2) Deleted crypto_acomp_batch_compress() and crypto_acomp_batch_decompress() interfaces, as per Herbert's suggestion. Batching is instead enabled by chaining the requests. For non-batching compressors, there is no request chaining involved. Both, batching and non-batching compressions are accomplished by zswap by calling: crypto_wait_req(crypto_acomp_compress(acomp_ctx->reqs[0]), &acomp_ctx->wait); 3) iaa_crypto implementation of batch compressions/decompressions using request chaining, as per Herbert's suggestions. 4) Simplification of the acomp_ctx resource allocation/deletion with respect to CPU hot[un]plug, to address Yosry's suggestions to explore the mutex options in zswap_cpu_comp_prepare(). Yosry, please let me know if the per-cpu memory cost of this proposed change is acceptable (IAA: 64.8KB, Software compressors: 8.2KB). On the positive side, I believe restarting reclaim on a CPU after it has been through an offline-online transition, will be much faster by not deleting the acomp_ctx resources when the CPU gets offlined. 5) Use of lockdep assertions rather than comments for internal locking rules, as per Yosry's suggestion. 6) No specific references to IAA in zswap.c, as suggested by Yosry. 7) Explored various solutions other than the v6 zswap_store_folio() implementation, to fix the zstd regression seen in v5, to attempt to unify common code paths, and to allocate smaller arrays for the zswap entries on the stack. All these options were found to cause usemem30 latency regression with zstd. The v6 version of zswap_store_folio() is the only implementation that does not cause zstd regression, confirmed by 10 consecutive runs, each giving quite consistent latency numbers. Hence, the v6 implementation is carried forward to v7, with changes for branching for batching vs. sequential compression API calls. Changes since v5: ================= 1) Rebased to mm-unstable as of 2-1-2025, commit 7de6fd8ab650. Several improvements, regression fixes and bug fixes, based on Yosry's v5 comments (Thanks Yosry!): 2) Fix for zstd performance regression in v5. 3) Performance debug and fix for marginal improvements with IAA batching vs. sequential. 4) Performance testing data compares IAA with and without batching, instead of IAA batching against zstd. 5) Commit logs/zswap comments not mentioning crypto_acomp implementation details. 6) Delete the pr_info_once() when batching resources are allocated in zswap_cpu_comp_prepare(). 7) Use kcalloc_node() for the multiple acomp_ctx buffers/reqs in zswap_cpu_comp_prepare(). 8) Simplify and consolidate error handling cleanup code in zswap_cpu_comp_prepare(). 9) Introduce zswap_compress_folio() in a separate patch. 10) Bug fix in zswap_store_folio() when xa_store() failure can cause all compressed objects and entries to be freed, and UAF when zswap_store() tries to free the entries that were already added to the xarray prior to the failure. 11) Deleting compressed_bytes/bytes. zswap_store_folio() also comprehends the recent fixes in commit bf5eaaaf7941 ("mm/zswap: fix inconsistency when zswap_store_page() fails") by Hyeonggon Yoo. iaa_crypto improvements/fixes/changes: 12) Enables asynchronous mode and makes it the default. With commit 4ebd9a5ca478 ("crypto: iaa - Fix IAA disabling that occurs when sync_mode is set to 'async'"), async mode was previously just sync. We now have true async support. 13) Change idxd descriptor allocations from blocking to non-blocking with timeouts, and mitigations for compress/decompress ops that fail to obtain a descriptor. This is a fix for tasks blocked errors seen in configurations where 30+ cores are running workloads under high memory pressure, and sending comps/decomps to 1 IAA device. 14) Fixes a bug with unprotected access of "deflate_generic_tfm" in deflate_generic_decompress(), which can cause data corruption and zswap_decompress() kernel crash. 15) zswap uses crypto_acomp_batch_compress() with async polling instead of request chaining for slightly better latency. However, the request chaining framework itself is unchanged, preserved from v5. Changes since v4: ================= 1) Rebased to mm-unstable as of 12-20-2024, commit 5555a83c82d6. 2) Added acomp request chaining, as suggested by Herbert. Thanks Herbert! 3) Implemented IAA compress batching using request chaining. 4) zswap_store() batching simplifications suggested by Chengming, Yosry and Nhat, thanks to all! - New zswap_compress_folio() that is called by zswap_store(). - Move the loop over folio's pages out of zswap_store() and into a zswap_store_folio() that stores all pages. - Allocate all zswap entries for the folio upfront. - Added zswap_batch_compress(). - Branch to call zswap_compress() or zswap_batch_compress() inside zswap_compress_folio(). - All iterations over pages kept in same function level. - No helpers other than the newly added zswap_store_folio() and zswap_compress_folio(). Changes since v3: ================= 1) Rebased to mm-unstable as of 11-18-2024, commit 5a7056135bb6. 2) Major re-write of iaa_crypto driver's mapping of IAA devices to cores, based on packages instead of NUMA nodes. 3) Added acomp_has_async_batching() API to crypto acomp, that allows zswap/zram to query if a crypto_acomp has registered batch_compress and batch_decompress interfaces. 4) Clear the poll bits on the acomp_reqs passed to iaa_comp_a[de]compress_batch() so that a module like zswap can be confident about the acomp_reqs[0] not having the poll bit set before calling the fully synchronous API crypto_acomp_[de]compress(). Herbert, I would appreciate it if you can review changes 2-4; in patches 1-8 in v4. I did not want to introduce too many iaa_crypto changes in v4, given that patch 7 is already making a major change. I plan to work on incorporating the request chaining using the ahash interface in v5 (I need to understand the basic crypto ahash better). Thanks Herbert! 5) Incorporated Johannes' suggestion to not have a sysctl to enable compress batching. 6) Incorporated Yosry's suggestion to allocate batching resources in the cpu hotplug onlining code, since there is no longer a sysctl to control batching. Thanks Yosry! 7) Incorporated Johannes' suggestions related to making the overall sequence of events between zswap_store() and zswap_batch_store() similar as much as possible for readability and control flow, better naming of procedures, avoiding forward declarations, not inlining error path procedures, deleting zswap internal details from zswap.h, etc. Thanks Johannes, really appreciate the direction! I have tried to explain the minimal future-proofing in terms of the zswap_batch_store() signature and the definition of "struct zswap_batch_store_sub_batch" in the comments for this struct. I hope the new code explains the control flow a bit better. Changes since v2: ================= 1) Rebased to mm-unstable as of 11-5-2024, commit 7994b7ea6ac8. 2) Fixed an issue in zswap_create_acomp_ctx() with checking for NULL returned by kmalloc_node() for acomp_ctx->buffers and for acomp_ctx->reqs. 3) Fixed a bug in zswap_pool_can_batch() for returning true if pool->can_batch_comp is found to be equal to BATCH_COMP_ENABLED, and if the per-cpu acomp_batch_ctx tests true for batching resources having been allocated on this cpu. Also, changed from per_cpu_ptr() to raw_cpu_ptr(). 4) Incorporated the zswap_store_propagate_errors() compilation warning fix suggested by Dan Carpenter. Thanks Dan! 5) Replaced the references to SWAP_CRYPTO_SUB_BATCH_SIZE in comments in zswap.h, with SWAP_CRYPTO_BATCH_SIZE. Changes since v1: ================= 1) Rebased to mm-unstable as of 11-1-2024, commit 5c4cf96cd702. 2) Incorporated Herbert's suggestions to use an acomp_req flag to indicate async/poll mode, and to encapsulate the polling functionality in the iaa_crypto driver. Thanks Herbert! 3) Incorporated Herbert's and Yosry's suggestions to implement the batching API in iaa_crypto and to make its use seamless from zswap's perspective. Thanks Herbert and Yosry! 4) Incorporated Yosry's suggestion to make it more convenient for the user to enable compress batching, while minimizing the memory footprint cost. Thanks Yosry! 5) Incorporated Yosry's suggestion to de-couple the shrink_folio_list() reclaim batching patch from this series, since it requires a broader discussion. I would greatly appreciate code review comments for the iaa_crypto driver and mm patches included in this series! Thanks, Kanchana Kanchana P Sridhar (14): crypto: acomp - Add synchronous/asynchronous acomp request chaining. crypto: acomp - New interfaces to facilitate batching support in acomp & drivers. crypto: iaa - Add an acomp_req flag CRYPTO_ACOMP_REQ_POLL to enable async mode. crypto: iaa - Implement batch compression/decompression with request chaining. crypto: iaa - Enable async mode and make it the default. crypto: iaa - Disable iaa_verify_compress by default. crypto: iaa - Re-organize the iaa_crypto driver code. crypto: iaa - Map IAA devices/wqs to cores based on packages instead of NUMA. crypto: iaa - Distribute compress jobs from all cores to all IAAs on a package. crypto: iaa - Descriptor allocation timeouts with mitigations in iaa_crypto. crypto: iaa - Fix for "deflate_generic_tfm" global being accessed without locks. mm: zswap: Simplify acomp_ctx resource allocation/deletion and mutex lock usage. mm: zswap: Allocate pool batching resources if the compressor supports batching. mm: zswap: Compress batching with request chaining in zswap_store() of large folios. .../driver-api/crypto/iaa/iaa-crypto.rst | 11 +- crypto/acompress.c | 285 +++ drivers/crypto/intel/iaa/iaa_crypto.h | 30 +- drivers/crypto/intel/iaa/iaa_crypto_main.c | 1556 ++++++++++++----- include/crypto/acompress.h | 79 + include/crypto/algapi.h | 10 + include/crypto/internal/acompress.h | 14 + include/linux/crypto.h | 39 + mm/zswap.c | 722 +++++--- 9 files changed, 2043 insertions(+), 703 deletions(-) base-commit: 5f089a9aa987ccf72df0c6955e168e865f280603