Messages in this thread | | | Date | Wed, 17 Dec 2014 10:10:43 -0600 (CST) | From | Christoph Lameter <> | Subject | Re: [PATCH 0/7] slub: Fastpath optimization (especially for RT) V1 |
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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>
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