Messages in this thread | | | Date | Thu, 18 Dec 2014 23:41:35 +0900 | Subject | Re: [PATCH 0/7] slub: Fastpath optimization (especially for RT) V1 | From | Joonsoo Kim <> |
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2014-12-18 1:10 GMT+09:00 Christoph Lameter <cl@linux.com>: > 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:
I checked my compiled code and it seems to be no problem. gcc (Ubuntu 4.8.2-19ubuntu1) 4.8.2
Thanks.
> 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> >
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