Re: [LKP] [timer] 17cdf560f27: +4.0% boot-meminfo.VmallocUsed

From: Peter Zijlstra
Date: Thu Apr 02 2015 - 03:55:01 EST


On Thu, Apr 02, 2015 at 09:06:09AM +0800, Huang Ying wrote:
> FYI, we noticed the below changes on
>
> git://git.kernel.org/pub/scm/linux/kernel/git/vireshk/linux.git timer/alloc_tvec_statically
> commit 17cdf560f2727f687ab159707d0aa591f8a2f82d ("timer: Allocate per-cpu tvec_base's statically")
>
>
> testbox/testcase/testparams: lkp-sbx04/boot/performance-1
>
> c5e77f5216abdd1d 17cdf560f2727f687ab159707d
> ---------------- --------------------------
> %stddev %change %stddev
> \ | \
> 410996 ± 0% +4.0% 427412 ± 0% boot-meminfo.VmallocUsed
>
> testbox/testcase/testparams: wsm/boot/performance-1
>
> c5e77f5216abdd1d 17cdf560f2727f687ab159707d
> ---------------- --------------------------
> 85712 ± 0% +2.4% 87772 ± 0% boot-meminfo.VmallocUsed
>
> testbox/testcase/testparams: lkp-snb01/boot/performance-1
>
> c5e77f5216abdd1d 17cdf560f2727f687ab159707d
> ---------------- --------------------------
> 447001 ± 0% -1.0% 442558 ± 0% boot-slabinfo.num_objs
> 125616 ± 5% -13.5% 108720 ± 4% boot-meminfo.DirectMap4k
> 347196 ± 0% +4.7% 363612 ± 0% boot-meminfo.VmallocUsed
>

well, duh.. it changes a dynamic allocation into a static per-cpu one.
What did you expect?
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