From: Joseph Qi <joseph.qi@huawei.com>
To: ocfs2-devel@oss.oracle.com
Subject: [Ocfs2-devel] [PATCH 0/7] ocfs2: allocate blocks in direct I/O write
Date: Wed, 17 Sep 2014 10:24:39 +0800 [thread overview]
Message-ID: <5418F0E7.8050503@huawei.com> (raw)
In-Reply-To: <20140910124227.fb91ca07159191d5aee73d33@linux-foundation.org>
Hi Andrew,
Currently in case of O_DIRECT append write (block not allocated yet),
ocfs2 will fall back to buffered I/O. This has some disadvantages.
Firstly, it is not the behavior as expected. Secondly, it will consume
huge page cache, e.g. in mass backup scenario. Thirdly, modern
filesystems such as ext4 support this feature.
So please consider, thanks.
On 2014/9/11 3:42, Andrew Morton wrote:
> On Wed, 10 Sep 2014 20:38:04 +0800 WeiWei Wang <wangww631@huawei.com> wrote:
>
>> hi all,
>> In ocfs2 append I/O write and fill holes I/O write situation, blocks have not been allocated yet, so the direct I/O write will fallback to buffer I/O write.
>> Buffer I/O write the data to page cache first, then flush the page cache to disk, this will consume some performance. In this patch, the direct I/O write
>> doesn't not need to fallback to buffer I/O write any more because the allocate blocks are enabled in direct I/O now.
>>
>
> The entire point of the patchset is to improve performance, but the
> changelog contains no performance measurements! How do we know it's
> worth considering? Please include quantitative benchmarking results
> in the changelog.
>
>
>
> _______________________________________________
> Ocfs2-devel mailing list
> Ocfs2-devel at oss.oracle.com
> https://oss.oracle.com/mailman/listinfo/ocfs2-devel
>
>
prev parent reply other threads:[~2014-09-17 2:24 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-10 12:38 [Ocfs2-devel] [PATCH 0/7] ocfs2: allocate blocks in direct I/O write WeiWei Wang
2014-09-10 19:42 ` Andrew Morton
2014-09-12 1:28 ` WeiWei Wang
2014-09-17 2:24 ` Joseph Qi [this message]
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