From: "Theodore Y. Ts'o" <tytso@mit.edu>
To: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Cc: linux-ext4@vger.kernel.org
Subject: Re: [PATCH 1/2] jbd2: add new tracepoint jbd2_sleep_on_shadow
Date: Wed, 11 Sep 2019 09:57:07 -0400 [thread overview]
Message-ID: <20190911135707.GC2740@mit.edu> (raw)
In-Reply-To: <5d96e18f-9610-208f-6db3-6a7b6a112400@linux.alibaba.com>
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?
Regards,
- Ted
next prev parent reply other threads:[~2019-09-11 14:00 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-02 14:54 [PATCH 1/2] jbd2: add new tracepoint jbd2_sleep_on_shadow Xiaoguang Wang
2019-09-02 14:54 ` [PATCH 2/2] jbd2: add new tracepoint jbd2_wait_on_transaction_locked Xiaoguang Wang
2019-09-07 16:21 ` [PATCH 1/2] jbd2: add new tracepoint jbd2_sleep_on_shadow Theodore Y. Ts'o
2019-09-11 6:52 ` Xiaoguang Wang
2019-09-11 13:57 ` Theodore Y. Ts'o [this message]
2019-09-16 14:20 ` Xiaoguang Wang
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