Re: Performance regressions in "boot_time" tests in Linux 5.8 Kernel

[Rahul Gopakumar]

Hi Baoquan,

To which commit should we apply the draft patch. We tried applying
the patch to the commit 3e4fb4346c781068610d03c12b16c0cfb0fd24a3
(the one we used for applying the previous patch) but it fails.


From: bhe@xxxxxxxxxx <bhe@xxxxxxxxxx>
Sent: 12 November 2020 8:21 PM
To: Rahul Gopakumar <gopakumarr@xxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx <linux-mm@xxxxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx <linux-kernel@xxxxxxxxxxxxxxx>; akpm@xxxxxxxxxxxxxxxxxxxx <akpm@xxxxxxxxxxxxxxxxxxxx>; natechancellor@xxxxxxxxx <natechancellor@xxxxxxxxx>; ndesaulniers@xxxxxxxxxx <ndesaulniers@xxxxxxxxxx>; clang-built-linux@xxxxxxxxxxxxxxxx <clang-built-linux@xxxxxxxxxxxxxxxx>; rostedt@xxxxxxxxxxx <rostedt@xxxxxxxxxxx>; Rajender M <manir@xxxxxxxxxx>; Yiu Cho Lau <lauyiuch@xxxxxxxxxx>; Peter Jonasson <pjonasson@xxxxxxxxxx>; Venkatesh Rajaram <rajaramv@xxxxxxxxxx>
Subject: Re: Performance regressions in "boot_time" tests in Linux 5.8 Kernel 
 
On 11/03/20 at 12:34pm, Rahul Gopakumar wrote:
> >> So, you mean with the draft patch applied, the initial performance
> regression goes away, just many page corruption errors with call trace
> are seen, right?
> 
> Yes, that's right.
> 
> >> And the performance regression is about 2sec delay in
> your system?
> 
> The delay due to this new page corruption issue is about
> 3 secs.
> 
> Here is the summary
> 
> * Initial problem - 2 secs
> * Draft patch - Fixes initial problem (recovers 2 secs) but
> brings in new page corruption issue (3 secs)
> 
> >> Could you tell how you setup vmware VM so that I can ask our QA for
> help to create a vmware VM for me to test?
> 
> * Use vSphere ESXi 6.7 or 7.0 GA.
> * Create VM using vSphere Web Client and specify 1TB VM Memory.
> * Install RHEL 8.1, that's the guest used in this test.

Can you try the attached draft patch?

> 
> With draft patch, you should be able to reproduce the issue.
> Let me know if you need more details.