Messages in this thread | | | Date | Thu, 03 May 2012 09:58:21 -0400 | From | Nitin Gupta <> | Subject | Re: [PATCH 4/4] zsmalloc: zsmalloc: align cache line size |
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On 5/3/12 2:40 AM, Minchan Kim wrote: > It's a overkill to align pool size with PAGE_SIZE to avoid > false-sharing. This patch aligns it with just cache line size. > > Signed-off-by: Minchan Kim<minchan@kernel.org> > --- > drivers/staging/zsmalloc/zsmalloc-main.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/staging/zsmalloc/zsmalloc-main.c b/drivers/staging/zsmalloc/zsmalloc-main.c > index 51074fa..3991b03 100644 > --- a/drivers/staging/zsmalloc/zsmalloc-main.c > +++ b/drivers/staging/zsmalloc/zsmalloc-main.c > @@ -489,14 +489,14 @@ fail: > > struct zs_pool *zs_create_pool(const char *name, gfp_t flags) > { > - int i, error, ovhd_size; > + int i, error; > struct zs_pool *pool; > > if (!name) > return NULL; > > - ovhd_size = roundup(sizeof(*pool), PAGE_SIZE); > - pool = kzalloc(ovhd_size, GFP_KERNEL); > + pool = kzalloc(ALIGN(sizeof(*pool), cache_line_size()), > + GFP_KERNEL);
a basic question: Is rounding off allocation size to cache_line_size enough to ensure that the object is cache-line-aligned? Isn't it possible that even though the object size is multiple of cache-line, it may still not be properly aligned and end up sharing cache line with some other read-mostly object?
Thanks, Nitin
> if (!pool) > return NULL; >
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