From: hch@infradead.org (Christoph Hellwig)
Subject: NVMe APST high latency power states being skipped
Date: Thu, 1 Jun 2017 04:32:06 -0700 [thread overview]
Message-ID: <20170601113206.GA29895@infradead.org> (raw)
In-Reply-To: <CAAd53p4qdk2ngC7-BNB++ZLKK39-MiUp22PT6wcsRzxCHzmniw@mail.gmail.com>
On Thu, Jun 01, 2017@04:19:26PM +0800, Kai-Heng Feng wrote:
> >> I did some benchmark on the high latency SanDisk A400:
> >> Kernel compilation, no PS3/PS4:
> >> real 23m36.466s
> >> user 115m49.944s
> >> sys 10m58.352s
> >>
> >> Kernel compilation, allow PS3/PS4:
> >> real 24m40.308s
> >> user 116m12.600s
> >> sys 11m47.484s
> >
> > That's quite a bit of a slow down. Can we play a bit with the
> > entry latency (maybe just for PS4) so that we still get into the
> > modes, but not as quickly?
>
> I changed the "Idle Time Prior to Transition" from 55000ms to 110000ms,
> The time to compile kernel source is roughly the same.
>
> My guess is that since the filesystem is constantly doing I/O while
> compiling kernel, nvme never (or rarely) hits PS4.
That doesn't explain why we need more than a minute more for the
compile. How reproducible are these numbers, btw?
next prev parent reply other threads:[~2017-06-01 11:32 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-22 9:04 NVMe APST high latency power states being skipped Kai-Heng Feng
2017-05-23 7:17 ` Christoph Hellwig
2017-05-23 8:06 ` Kai-Heng Feng
2017-05-23 9:42 ` Christoph Hellwig
2017-05-23 19:35 ` Andy Lutomirski
2017-05-23 19:56 ` Mario.Limonciello
2017-05-23 20:01 ` Andy Lutomirski
2017-05-23 20:19 ` Mario.Limonciello
2017-05-23 21:11 ` Andy Lutomirski
2017-05-23 22:09 ` Mario.Limonciello
2017-05-24 4:53 ` Kai-Heng Feng
2017-05-24 5:31 ` Andy Lutomirski
2017-05-25 8:21 ` Kai-Heng Feng
2017-05-26 9:25 ` Christoph Hellwig
2017-06-01 8:19 ` Kai-Heng Feng
2017-06-01 11:32 ` Christoph Hellwig [this message]
2017-06-02 7:08 ` Kai-Heng Feng
2017-06-02 7:13 ` Christoph Hellwig
2017-06-06 9:54 ` Christoph Hellwig
2017-06-06 15:57 ` Andy Lutomirski
2017-06-07 6:19 ` Kai-Heng Feng
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