| Message ID | 20210920174713.4998-1-l4stpr0gr4m@gmail.com (mailing list archive) |
|---|---|
| State | RFC |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [RFC,net-next] Introducing lockless cache built on top of slab allocator | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Link |
| netdev/fixes_present | success | Link |
| netdev/patch_count | success | Link |
| netdev/tree_selection | success | Clearly marked for net-next |
| netdev/subject_prefix | success | Link |
| netdev/cc_maintainers | success | CCed 10 of 10 maintainers |
| netdev/source_inline | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Link |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/build_32bit | fail | Errors and warnings before: 5 this patch: 9 |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/verify_fixes | success | Link |
| netdev/checkpatch | warning | WARNING: line length of 82 exceeds 80 columns WARNING: line length of 89 exceeds 80 columns |
| netdev/build_allmodconfig_warn | fail | Errors and warnings before: 5 this patch: 9 |
| netdev/header_inline | success | Link |
2021년 9월 21일 (화) 오전 5:50, Jakub Kicinski <kuba@kernel.org>님이 작성: > > On Tue, 21 Sep 2021 02:47:13 +0900 Kangmin Park wrote: > > It is just introducing and proof of concept. > > The patch code is based on other RFC patches. So, the code is not > > correct yet, it is just simple proof of concept. > > > > Recently block layer implemented percpu, lockless cache on the top > > of slab allocator. It can be used for IO polling. > > > > Link: https://lwn.net/Articles/868070/ > > Link: https://www.spinics.net/lists/linux-block/msg71964.html > > > > It gained some IOPS increase (performance increased by about 10% > > on the block layer). > > > > And there are attempts to implement the percpu, lockless cache. > > > > Link: https://lore.kernel.org/linux-mm/20210920154816.31832-1-42.hyeyoo@gmail.com/T/#u > > > > If this cache is implemented successfully, > > how about use this cache to allocate skb instead of kmem_cache_alloc_bulk() > > in napi_skb_cache_get()? > > > > I want your comment/opinion. > > Please take a look at skb cache in struct napi_alloc_cache. > That should be your target here. > Oh, thanks for the advice. I'll send you a v2 patch to replace/improve napi_alloc_cache when progress is made in implementing the lockless cache. Best Regards, Kangmin Park > > Signed-off-by: Kangmin Park <l4stpr0gr4m@gmail.com> > > --- > > net/core/skbuff.c | 14 +++++++++----- > > 1 file changed, 9 insertions(+), 5 deletions(-) > > > > diff --git a/net/core/skbuff.c b/net/core/skbuff.c > > index 7c2ab27fcbf9..f9a9deca423d 100644 > > --- a/net/core/skbuff.c > > +++ b/net/core/skbuff.c > > @@ -170,11 +170,15 @@ static struct sk_buff *napi_skb_cache_get(void) > > struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache); > > struct sk_buff *skb; > > > > - if (unlikely(!nc->skb_count)) > > - nc->skb_count = kmem_cache_alloc_bulk(skbuff_head_cache, > > - GFP_ATOMIC, > > - NAPI_SKB_CACHE_BULK, > > - nc->skb_cache); > > + if (unlikely(!nc->skb_count)) { > > + /* kmem_cache_alloc_cached should be changed to return the size of > > + * the allocated cache > > + */ > > + nc->skb_cache = kmem_cache_alloc_cached(skbuff_head_cache, > > + GFP_ATOMIC | SLB_LOCKLESS_CACHE); > > + nc->skb_count = this_cpu_ptr(skbuff_head_cache)->size; > > + } > > + > > if (unlikely(!nc->skb_count)) > > return NULL; > >
diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 7c2ab27fcbf9..f9a9deca423d 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -170,11 +170,15 @@ static struct sk_buff *napi_skb_cache_get(void) struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache); struct sk_buff *skb; - if (unlikely(!nc->skb_count)) - nc->skb_count = kmem_cache_alloc_bulk(skbuff_head_cache, - GFP_ATOMIC, - NAPI_SKB_CACHE_BULK, - nc->skb_cache); + if (unlikely(!nc->skb_count)) { + /* kmem_cache_alloc_cached should be changed to return the size of + * the allocated cache + */ + nc->skb_cache = kmem_cache_alloc_cached(skbuff_head_cache, + GFP_ATOMIC | SLB_LOCKLESS_CACHE); + nc->skb_count = this_cpu_ptr(skbuff_head_cache)->size; + } + if (unlikely(!nc->skb_count)) return NULL;
It is just introducing and proof of concept. The patch code is based on other RFC patches. So, the code is not correct yet, it is just simple proof of concept. Recently block layer implemented percpu, lockless cache on the top of slab allocator. It can be used for IO polling. Link: https://lwn.net/Articles/868070/ Link: https://www.spinics.net/lists/linux-block/msg71964.html It gained some IOPS increase (performance increased by about 10% on the block layer). And there are attempts to implement the percpu, lockless cache. Link: https://lore.kernel.org/linux-mm/20210920154816.31832-1-42.hyeyoo@gmail.com/T/#u If this cache is implemented successfully, how about use this cache to allocate skb instead of kmem_cache_alloc_bulk() in napi_skb_cache_get()? I want your comment/opinion. Signed-off-by: Kangmin Park <l4stpr0gr4m@gmail.com> --- net/core/skbuff.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-)