linux-ext4 - Re: [PATCH 1/2] jbd2: add new tracepoint jbd2_sleep_on

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:   Mon, 16 Sep 2019 22:20:54 +0800
From:   Xiaoguang Wang <xiaoguang.wang@...ux.alibaba.com>
To:     "Theodore Y. Ts'o" <tytso@....edu>
Cc:     linux-ext4@...r.kernel.org
Subject: Re: [PATCH 1/2] jbd2: add new tracepoint jbd2_sleep_on_shadow

hi,

> On Wed, Sep 11, 2019 at 02:52:51PM +0800, Xiaoguang Wang wrote:
>>> I think maybe it might be better to use units of microseconds and then
>>> change sleep to usleep so the units are clear?  This is a spinlock, so
>>> it should be quick.
>>
>> Sorry, I may not quite understand you, do you mean that milliseconds is not precise, so
>> should use microseconds? For these two patches, they do not use usleep or msleep to do
>> real sleep work, they just record the duration which process takes to wait bh_shadow flag
>> to be cleared or transaction to be unlocked.
> 
> Apologies, I should have been clear enough.  Yes, my concern that
> milliseconds might not be fine-grained enough.  The sample results
> which you showed had values of 2ms, 1ms, and 0ms.  And the single 0ms
> result in particular raised the concern that we should use a
> microseconds instead of milliseconds.
> 
> In fact, instead of "sleep", maybe "latency(us)" or "latency(ms)"
> would be a better label?
OK, I'll update a v2, thanks.

Regards,
Xiaoguang Wang

> 
> Regards,
> 
> 						- Ted
>