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Groups > linux.kernel > #1548296
| From | Mel Gorman <mgorman@techsingularity.net> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH] mm, page_alloc: convert page_group_by_mobility_disable to static key |
| Date | 2016-12-29 13:10 +0100 |
| Message-ID | <sTHGW-6pF-29@gated-at.bofh.it> (permalink) |
| References | <sQsXL-6e4-5@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Tue, Dec 20, 2016 at 02:43:12PM +0100, Vlastimil Babka wrote: > The flag is rarely enabled or even changed, so it's an ideal static key > candidate. Since it's being checked in the page allocator fastpath via > gfpflags_to_migratetype(), it may actually save some valuable cycles. > > Here's a diff excerpt from __alloc_pages_nodemask() assembly: > > -movl page_group_by_mobility_disabled(%rip), %ecx > +.byte 0x0f,0x1f,0x44,0x00,0 > movl %r9d, %eax > shrl $3, %eax > andl $3, %eax > -testl %ecx, %ecx > -movl $0, %ecx > -cmovne %ecx, %eax > > I.e. a NOP instead of test, conditional move and some assisting moves. > > Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Mel Gorman <mgorman@techsingularity.net> -- Mel Gorman SUSE Labs
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[PATCH] mm, page_alloc: convert page_group_by_mobility_disable to static key Vlastimil Babka <vbabka@suse.cz> - 2016-12-20 14:50 +0100 Re: [PATCH] mm, page_alloc: convert page_group_by_mobility_disable to static key Mel Gorman <mgorman@techsingularity.net> - 2016-12-29 13:10 +0100 Re: [PATCH] mm, page_alloc: convert page_group_by_mobility_disable to static key Rik van Riel <riel@redhat.com> - 2016-12-29 17:10 +0100
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