Re: [LKP] [lkp-robot] [mm] 9092c71bb7: blogbench.write_score -12.3% regression

Hi, Chris,

Chris Mason [off-list ref] writes:

On 19 Jun 2018, at 23:51, Huang, Ying wrote:

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"Huang, Ying" [off-list ref] writes:

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Hi, Josef,

Do you have time to take a look at the regression?

kernel test robot [off-list ref] writes:

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Greeting,

FYI, we noticed a -12.3% regression of blogbench.write_score and
a +9.6% improvement
of blogbench.read_score due to commit:


commit: 9092c71bb724dba2ecba849eae69e5c9d39bd3d2 ("mm: use
sc->priority for slab shrink targets")
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git
master

in testcase: blogbench
on test machine: 16 threads Intel(R) Xeon(R) CPU D-1541 @
2.10GHz with 8G memory
with following parameters:

	disk: 1SSD
	fs: btrfs
	cpufreq_governor: performance

test-description: Blogbench is a portable filesystem benchmark
that tries to reproduce the load of a real-world busy file
server.
test-url:

I'm surprised, this patch is a big win in production here at FB.  I'll
have to reproduce these results to better understand what is going on.
My first guess is that since we have fewer inodes in slab, we're
reading more inodes from disk in order to do the writes.

But that should also make our read scores lower.

Any update on this?

Best Regards,
Huang, Ying