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 v2 2/4] percpu_stats: Enable 64-bit counts in 32-bit architectures
Date: Fri, 8 Apr 2016 13:46:28 -0400 [thread overview]
Message-ID: <20160408174628.GN24661@htj.duckdns.org> (raw)
In-Reply-To: <5707EB44.9020703@hpe.com>
Hello,
On Fri, Apr 08, 2016 at 01:32:52PM -0400, Waiman Long wrote:
> Yes, I think it will be more efficient to use percpu_counter in this case.
> The preempt_disable/enable() calls are pretty cheap. Once in a while, you
> need to take the lock and update the global count. How about I change the
> 2nd patch to use percpu_counter internally when 64-bit counts are needed in
> 32-bit archs, but use the regular percpu counts on 64-bit archs? If you are
> OK with that, I can update the patch accordingly.
Does having percpu_stats as a separate construct make sense after
that? Just use percpu_counter directly? You end up wasting a bit
more space that way but most of space overhead for these things are in
percpu part anyway, so in proportion it shouldn't make that much of a
difference.
Thanks.
--
tejun
next prev parent reply other threads:[~2016-04-08 17:46 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-08 16:16 [PATCH v2 0/4] ext4: Improve parallel I/O performance on NVDIMM Waiman Long
2016-04-08 16:16 ` [PATCH v2 1/4] percpu_stats: Simple per-cpu statistics count helper functions Waiman Long
2016-04-08 16:49 ` kbuild test robot
2016-04-08 17:45 ` kbuild test robot
2016-04-08 16:16 ` [PATCH v2 2/4] percpu_stats: Enable 64-bit counts in 32-bit architectures Waiman Long
2016-04-08 16:47 ` Tejun Heo
2016-04-08 17:32 ` Waiman Long
2016-04-08 17:46 ` Tejun Heo [this message]
2016-04-08 18:45 ` Waiman Long
2016-04-11 22:17 ` Tejun Heo
2016-04-12 18:15 ` Waiman Long
2016-04-08 16:16 ` [PATCH v2 3/4] ext4: Pass in DIO_SKIP_DIO_COUNT flag if inode_dio_begin() called Waiman Long
2016-04-08 16:16 ` [PATCH v2 4/4] ext4: Make cache hits/misses per-cpu counts Waiman Long
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