Messages in this thread | | | Date | Wed, 3 Apr 2024 09:25:33 +0200 | Subject | Re: [PATCH 3/4] mm/slub: simplify get_partial_node() | From | Vlastimil Babka <> |
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On 4/3/24 2:37 AM, Song, Xiongwei wrote: >> >> >> It could be tempting to use >= instead of > to achieve the same effect but >> that would have unintended performance effects that would best be evaluated >> separately. > > I can run a test to measure Amean changes. But in terms of x86 assembly, there > should not be extra instructions with ">=". > > Did a simple test, for ">=" it uses "jle" instruction, while "jl" instruction is used for ">". > No more instructions involved. So there should not be performance effects on x86.
Right, I didn't mean the code of the test, but how the difference of the comparison affects how many cpu partial slabs would be put on the cpu partial list here.
> Thanks, > Xiongwei > >> >> > >> > + put_cpu_partial(s, slab, 0); >> > + stat(s, CPU_PARTIAL_NODE); >> > + partial_slabs++; >> > + >> > + if (partial_slabs > slub_get_cpu_partial(s) / 2) >> > + break; >> > } >> > spin_unlock_irqrestore(&n->list_lock, flags); >> > return partial; >
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