lkml.org 
[lkml]   [2014]   [Dec]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 0/7] slub: Fastpath optimization (especially for RT) V1
On Wed, 17 Dec 2014, Joonsoo Kim wrote:

> + do {
> + tid = this_cpu_read(s->cpu_slab->tid);
> + c = this_cpu_ptr(s->cpu_slab);
> + } while (IS_ENABLED(CONFIG_PREEMPT) && unlikely(tid != c->tid));


Assembly code produced is a bit weird. I think the compiler undoes what
you wanted to do:

46fb: 49 8b 1e mov (%r14),%rbx rbx = c =s->cpu_slab?
46fe: 65 4c 8b 6b 08 mov %gs:0x8(%rbx),%r13 r13 = tid
4703: e8 00 00 00 00 callq 4708 <kmem_cache_alloc+0x48> ??
4708: 89 c0 mov %eax,%eax ??
470a: 48 03 1c c5 00 00 00 add 0x0(,%rax,8),%rbx ??
4711: 00
4712: 4c 3b 6b 08 cmp 0x8(%rbx),%r13 tid == c->tid
4716: 49 89 d8 mov %rbx,%r8
4719: 75 e0 jne 46fb <kmem_cache_alloc+0x3b>



\
 
 \ /
  Last update: 2014-12-17 17:41    [W:0.104 / U:0.032 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site