From: Fengguang Wu <fengguang.wu@intel.com>
To: Namjae Jeon <linkinjeon@gmail.com>
Cc: Jan Kara <jack@suse.cz>, Dave Chinner <david@fromorbit.com>,
linux-kernel@vger.kernel.org,
Namjae Jeon <namjae.jeon@samsung.com>,
Vivek Trivedi <t.vivek@samsung.com>,
Linux Memory Management List <linux-mm@kvack.org>,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH v3 2/2] Documentation: add description of dirty_background_centisecs
Date: Thu, 20 Sep 2012 16:45:07 +0800 [thread overview]
Message-ID: <20120920084507.GB5697@localhost> (raw)
In-Reply-To: <1347798364-2864-1-git-send-email-linkinjeon@gmail.com>
[ add CC ]
On Sun, Sep 16, 2012 at 08:26:04AM -0400, Namjae Jeon wrote:
> From: Namjae Jeon <namjae.jeon@samsung.com>
>
> This commit adds dirty_background_centisecs description in bdi sysfs
> documentation.
>
> Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
> Signed-off-by: Vivek Trivedi <t.vivek@samsung.com>
> ---
> Documentation/ABI/testing/sysfs-class-bdi | 25 +++++++++++++++++++++++++
> 1 file changed, 25 insertions(+)
>
> diff --git a/Documentation/ABI/testing/sysfs-class-bdi b/Documentation/ABI/testing/sysfs-class-bdi
> index 5f50097..6869736 100644
> --- a/Documentation/ABI/testing/sysfs-class-bdi
> +++ b/Documentation/ABI/testing/sysfs-class-bdi
> @@ -48,3 +48,28 @@ max_ratio (read-write)
> most of the write-back cache. For example in case of an NFS
> mount that is prone to get stuck, or a FUSE mount which cannot
> be trusted to play fair.
> +
> +dirty_background_centisecs (read-write)
> +
> + It is used to start early writeback of given bdi once bdi dirty
> + data exceeds product of average write bandwidth and
> + dirty_background_centisecs. It works in parallel of
> + dirty_writeback_centsecs and dirty_expire_interval based periodic
> + flushing mechanism.
> +
> + It is mainly useful for tuning writeback speed at 'NFS Server'
> + sothat NFS client could see better write speed.
> + A good use case is setting it to around 100 (1 second) in the NFS
> + server for improving NFS write performance. Note that it's not
> + recommended to set it to a too small value, which might lead to
> + unnecessary flushing for small IO size.
> + Setting it to 0 disables the feature.
> +
> + However, sometimes it may not match user expectations as it is based
> + on bdi write bandwidth estimation. The users should not expect this
> + threshold to work accurately.
> + Write bandwidth estimation is a best effort to estimate bdi write
> + speed bandwidth. But it can be wildly wrong in certain situations
> + such as sudden change of workload (including the workload startup
> + stage), or if there are no heavy writes since boot, in which case
> + there is no reasonable estimation yet.
> --
> 1.7.9.5
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
prev parent reply other threads:[~2012-09-20 8:45 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-16 12:26 [PATCH v3 2/2] Documentation: add description of dirty_background_centisecs Namjae Jeon
2012-09-20 8:45 ` Fengguang Wu [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20120920084507.GB5697@localhost \
--to=fengguang.wu@intel.com \
--cc=david@fromorbit.com \
--cc=jack@suse.cz \
--cc=linkinjeon@gmail.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=namjae.jeon@samsung.com \
--cc=t.vivek@samsung.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).