From: Tejun Heo <tj@kernel.org>
To: Waiman Long <waiman.long@hpe.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>,
Andreas Dilger <adilger.kernel@dilger.ca>,
Christoph Lameter <cl@linux.com>,
linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org,
Scott J Norton <scott.norton@hpe.com>,
Douglas Hatch <doug.hatch@hpe.com>,
Toshimitsu Kani <toshi.kani@hpe.com>
Subject: Re: [PATCH 2/3] percpu_stats: Simple per-cpu statistics count helper functions
Date: Thu, 7 Apr 2016 16:41:14 -0400 [thread overview]
Message-ID: <20160407204114.GJ7822@mtj.duckdns.org> (raw)
In-Reply-To: <5706C4F2.6020108@hpe.com>
Hello, Waiman.
On Thu, Apr 07, 2016 at 04:37:06PM -0400, Waiman Long wrote:
> I would say that because I am lazy, I don't want compute the deltas every
> time I want to see the effect of running a certain type of workload on the
> statistics counts. I have use case that I need to track 10 or so statistics
> counts and monitor their changes after running a job. It is much more
> convenient to do a reset and see what you get than doing manual subtractions
> to find out.
I don't know. Write a simple script? Even if you wanna keep it in
kernel, you can just have a base counter which offsets the summed up
value on read.
> I had taken a look at percpu-refcount.[ch]. I think the synchronization code
> is a bit overkill for this purpose as no one really need a very precise
> statistics counts nor precise atomic reset. I would prefer providing an
> optional atomic reset feature with slower statistics count update path for
> the time being. If we come across a use case where we need atomic reset with
> negligible slowdown, we could then refactor the code to use something
> similar to what the percpu-refcount code is doing.
Please either drop reset or make it actually work; otherwise, I don't
think this should go in.
Thanks.
--
tejun
next prev parent reply other threads:[~2016-04-07 20:41 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-02 3:09 [PATCH 0/3] ext4: Improve parallel I/O performance on NVDIMM Waiman Long
2016-04-02 3:09 ` [PATCH 1/3] ext4: Pass in DIO_SKIP_DIO_COUNT flag if inode_dio_begin() called Waiman Long
2016-04-02 3:09 ` [PATCH 2/3] percpu_stats: Simple per-cpu statistics count helper functions Waiman Long
2016-04-04 7:36 ` Nikolay Borisov
2016-04-04 17:11 ` Waiman Long
2016-04-04 19:09 ` Christoph Lameter
2016-04-06 21:53 ` Waiman Long
2016-04-04 16:02 ` Tejun Heo
2016-04-06 19:52 ` Waiman Long
2016-04-06 21:51 ` Waiman Long
2016-04-06 22:54 ` Tejun Heo
2016-04-07 15:58 ` Waiman Long
2016-04-07 16:06 ` Tejun Heo
2016-04-07 18:52 ` Waiman Long
2016-04-07 18:58 ` Tejun Heo
2016-04-07 20:37 ` Waiman Long
2016-04-07 20:41 ` Tejun Heo [this message]
2016-04-07 21:38 ` Waiman Long
2016-04-02 3:09 ` [PATCH 3/3] ext4: Make cache hits/misses per-cpu counts Waiman Long
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