| Message ID | 20190916144558.27282-1-lpf.vector@gmail.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | mm, slab: Make kmalloc_info[] contain all types of names | expand |
On Mon, 16 Sep 2019, Pengfei Li wrote: > The name of KMALLOC_NORMAL is contained in kmalloc_info[].name, > but the names of KMALLOC_RECLAIM and KMALLOC_DMA are dynamically > generated by kmalloc_cache_name(). > > Patch1 predefines the names of all types of kmalloc to save > the time spent dynamically generating names. > > These changes make sense, and the time spent by new_kmalloc_cache() > has been reduced by approximately 36.3%. This is time spend during boot and does not affect later system performance. > Time spent by new_kmalloc_cache() > (CPU cycles) > 5.3-rc7 66264 > 5.3-rc7+patch_1-3 42188 Ok. 15k cycles during boot saved. So we save 5 microseconds during bootup? The current approach was created with the view on future setups allowing a dynamic configuration of kmalloc caches based on need. I.e. ZONE_DMA may not be needed once the floppy driver no longer makes use of it.
On Tue, Sep 17, 2019 at 12:04 AM Christopher Lameter <cl@linux.com> wrote: > > On Mon, 16 Sep 2019, Pengfei Li wrote: > > > The name of KMALLOC_NORMAL is contained in kmalloc_info[].name, > > but the names of KMALLOC_RECLAIM and KMALLOC_DMA are dynamically > > generated by kmalloc_cache_name(). > > > > Patch1 predefines the names of all types of kmalloc to save > > the time spent dynamically generating names. > > > > These changes make sense, and the time spent by new_kmalloc_cache() > > has been reduced by approximately 36.3%. > > This is time spend during boot and does not affect later system > performance. > Yes. > > Time spent by new_kmalloc_cache() > > (CPU cycles) > > 5.3-rc7 66264 > > 5.3-rc7+patch_1-3 42188 > > Ok. 15k cycles during boot saved. So we save 5 microseconds during bootup? > Yes, this is a very small benefit. > The current approach was created with the view on future setups allowing a > dynamic configuration of kmalloc caches based on need. I.e. ZONE_DMA may > not be needed once the floppy driver no longer makes use of it. Yes, With this in mind, I also used #ifdef for INIT_KMALLOC_INFO.
Changes in v5 -- 1. patch 1/7: - rename SET_KMALLOC_SIZE to INIT_KMALLOC_INFO 2. patch 5/7: - fix build errors (Reported-by: kbuild test robot) - make all_kmalloc_info[] static (Reported-by: kbuild test robot) 3. patch 6/7: - for robustness, determine kmalloc_cache is !NULL in new_kmalloc_cache() 4. add ack tag from David Rientjes Changes in v4 -- 1. [old] abandon patch 4/4 2. [new] patch 4/7: - return ZERO_SIZE_ALLOC instead 0 for zero sized requests 3. [new] patch 5/7: - reorder kmalloc_info[], kmalloc_caches[] (in order of size) - hard to split, so slightly larger 4. [new] patch 6/7: - initialize kmalloc_cache[] with the same size but different types 5. [new] patch 7/7: - modify kmalloc_caches[type][idx] to kmalloc_caches[idx][type] Patch 4-7 are newly added, more information can be obtained from commit messages. Changes in v3 -- 1. restore __initconst (patch 1/4) 2. rename patch 3/4 3. add more clarification for patch 4/4 4. add ack tag from Roman Gushchin Changes in v2 -- 1. remove __initconst (patch 1/5) 2. squash patch 2/5 3. add ack tag from Vlastimil Babka There are three types of kmalloc, KMALLOC_NORMAL, KMALLOC_RECLAIM and KMALLOC_DMA. The name of KMALLOC_NORMAL is contained in kmalloc_info[].name, but the names of KMALLOC_RECLAIM and KMALLOC_DMA are dynamically generated by kmalloc_cache_name(). Patch1 predefines the names of all types of kmalloc to save the time spent dynamically generating names. These changes make sense, and the time spent by new_kmalloc_cache() has been reduced by approximately 36.3%. Time spent by new_kmalloc_cache() (CPU cycles) 5.3-rc7 66264 5.3-rc7+patch_1-3 42188 bloat-o-meter -- $ ./scripts/bloat-o-meter vmlinux_5.3 vmlinux_5.3+patch_1-7 add/remove: 1/2 grow/shrink: 6/65 up/down: 872/-1574 (-702) Function old new delta all_kmalloc_info - 832 +832 crypto_create_tfm 211 225 +14 ieee80211_key_alloc 1159 1169 +10 nl80211_parse_sched_scan 2787 2795 +8 tg3_self_test 4255 4259 +4 find_get_context.isra 634 637 +3 sd_probe 947 948 +1 nf_queue 671 670 -1 trace_parser_get_init 71 69 -2 pkcs7_verify.cold 318 316 -2 units 323 320 -3 nl80211_set_reg 642 639 -3 pkcs7_verify 1503 1495 -8 i915_sw_fence_await_dma_fence 445 437 -8 nla_strdup 143 134 -9 kmalloc_slab 102 93 -9 xhci_alloc_tt_info 349 338 -11 xhci_segment_alloc 303 289 -14 xhci_alloc_container_ctx 221 207 -14 xfrm_policy_alloc 277 263 -14 selinux_sk_alloc_security 119 105 -14 sdev_evt_send_simple 124 110 -14 sdev_evt_alloc 85 71 -14 sbitmap_queue_init_node 424 410 -14 regulatory_hint_found_beacon 400 386 -14 nf_ct_tmpl_alloc 91 77 -14 gss_create_cred 146 132 -14 drm_flip_work_allocate_task 76 62 -14 cfg80211_stop_iface 266 252 -14 cfg80211_sinfo_alloc_tid_stats 83 69 -14 cfg80211_port_authorized 218 204 -14 cfg80211_ibss_joined 341 327 -14 call_usermodehelper_setup 155 141 -14 bpf_prog_alloc_no_stats 188 174 -14 blk_alloc_flush_queue 197 183 -14 bdi_alloc_node 201 187 -14 _netlbl_catmap_getnode 253 239 -14 __igmp_group_dropped 629 615 -14 ____ip_mc_inc_group 481 467 -14 xhci_alloc_command 221 205 -16 audit_log_d_path 204 188 -16 xprt_switch_alloc 145 128 -17 xhci_ring_alloc 378 361 -17 xhci_mem_init 3673 3656 -17 xhci_alloc_virt_device 505 488 -17 xhci_alloc_stream_info 727 710 -17 tcp_sendmsg_locked 3129 3112 -17 tcp_md5_do_add 783 766 -17 tcp_fastopen_defer_connect 279 262 -17 sr_read_tochdr.isra 260 243 -17 sr_read_tocentry.isra 337 320 -17 sr_is_xa 385 368 -17 sr_get_mcn 269 252 -17 scsi_probe_and_add_lun 2947 2930 -17 ring_buffer_read_prepare 103 86 -17 request_firmware_nowait 405 388 -17 ohci_urb_enqueue 3185 3168 -17 nfs_alloc_seqid 96 79 -17 nfs4_get_state_owner 1049 1032 -17 nfs4_do_close 587 570 -17 mempool_create_node 173 156 -17 ip6_setup_cork 1030 1013 -17 ida_alloc_range 951 934 -17 gss_import_sec_context 187 170 -17 dma_pool_alloc 419 402 -17 devres_open_group 223 206 -17 cfg80211_parse_mbssid_data 2406 2389 -17 ip_setup_cork 374 354 -20 kmalloc_caches 336 312 -24 __i915_sw_fence_await_sw_fence 429 405 -24 kmalloc_cache_name 57 - -57 create_kmalloc_caches 270 195 -75 new_kmalloc_cache 112 - -112 kmalloc_info 432 8 -424 Total: Before=14789209, After=14788507, chg -0.00% Pengfei Li (7): mm, slab: Make kmalloc_info[] contain all types of names mm, slab: Remove unused kmalloc_size() mm, slab_common: Use enum kmalloc_cache_type to iterate over kmalloc caches mm, slab: Return ZERO_SIZE_ALLOC for zero sized kmalloc requests mm, slab_common: Make kmalloc_caches[] start at size KMALLOC_MIN_SIZE mm, slab_common: Initialize the same size of kmalloc_caches[] mm, slab_common: Modify kmalloc_caches[type][idx] to kmalloc_caches[idx][type] include/linux/slab.h | 136 ++++++++++++++------------ mm/slab.c | 11 ++- mm/slab.h | 10 +- mm/slab_common.c | 227 ++++++++++++++++++------------------------- mm/slub.c | 12 +-- 5 files changed, 187 insertions(+), 209 deletions(-)