From: Fengguang Wu <fengguang.wu@intel.com>
To: YingHang Zhu <casualfisher@gmail.com>
Cc: Dave Chinner <david@fromorbit.com>,
akpm@linux-foundation.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH] mm: readahead: remove redundant ra_pages in file_ra_state
Date: Thu, 25 Oct 2012 10:38:08 +0800 [thread overview]
Message-ID: <20121025023808.GA23462@localhost> (raw)
In-Reply-To: <CAA9v8mEULAEHn8qSsFokEue3c0hy8pK8bkYB+6xOtz_Tgbp0vw@mail.gmail.com>
Hi YingHang,
> Actually I've talked about it with Fengguang, he advised we should unify the
> ra_pages in struct bdi and file_ra_state and leave the issue that
> spreading data
> across disks as it is.
> Fengguang, what's you opinion about this?
Yeah the two ra_pages may run out of sync for already opened files,
which could be a problem for long opened files. However as Dave put
it, a device's max readahead size is typically a static value that can
be set at mount time. So, the question is: do you really hurt from the
old behavior that deserves this code change?
I agree with Dave that the multi-disk case is not a valid concern. In
fact, how can the patch help that case? I mean, if it's two fuse files
lying in two disks, it *was* not a problem at all. If it's one big
file spreading to two disks, it's a too complex scheme to be
practically manageable which I doubt if you have such a setup.
Thanks,
Fengguang
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WARNING: multiple messages have this Message-ID (diff)
From: Fengguang Wu <fengguang.wu@intel.com>
To: YingHang Zhu <casualfisher@gmail.com>
Cc: Dave Chinner <david@fromorbit.com>,
akpm@linux-foundation.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH] mm: readahead: remove redundant ra_pages in file_ra_state
Date: Thu, 25 Oct 2012 10:38:08 +0800 [thread overview]
Message-ID: <20121025023808.GA23462@localhost> (raw)
In-Reply-To: <CAA9v8mEULAEHn8qSsFokEue3c0hy8pK8bkYB+6xOtz_Tgbp0vw@mail.gmail.com>
Hi YingHang,
> Actually I've talked about it with Fengguang, he advised we should unify the
> ra_pages in struct bdi and file_ra_state and leave the issue that
> spreading data
> across disks as it is.
> Fengguang, what's you opinion about this?
Yeah the two ra_pages may run out of sync for already opened files,
which could be a problem for long opened files. However as Dave put
it, a device's max readahead size is typically a static value that can
be set at mount time. So, the question is: do you really hurt from the
old behavior that deserves this code change?
I agree with Dave that the multi-disk case is not a valid concern. In
fact, how can the patch help that case? I mean, if it's two fuse files
lying in two disks, it *was* not a problem at all. If it's one big
file spreading to two disks, it's a too complex scheme to be
practically manageable which I doubt if you have such a setup.
Thanks,
Fengguang
next prev parent reply other threads:[~2012-10-25 2:38 UTC|newest]
Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-23 12:46 [PATCH] mm: readahead: remove redundant ra_pages in file_ra_state Ying Zhu
2012-10-23 12:46 ` Ying Zhu
2012-10-23 13:21 ` Ni zhan Chen
2012-10-23 13:21 ` Ni zhan Chen
[not found] ` <CAA9v8mGMa3SDD1OLTG_wdhCGx7K-0kvSV1+MRi9uCGTz6zZaLg@mail.gmail.com>
2012-10-23 13:41 ` YingHang Zhu
2012-10-23 13:41 ` YingHang Zhu
2012-10-24 1:02 ` Ni zhan Chen
2012-10-24 1:02 ` Ni zhan Chen
2012-10-24 1:33 ` YingHang Zhu
2012-10-24 1:33 ` YingHang Zhu
2012-10-23 22:47 ` Dave Chinner
2012-10-23 22:47 ` Dave Chinner
2012-10-23 23:53 ` YingHang Zhu
2012-10-23 23:53 ` YingHang Zhu
2012-10-24 20:19 ` Dave Chinner
2012-10-24 20:19 ` Dave Chinner
2012-10-25 0:17 ` YingHang Zhu
2012-10-25 0:17 ` YingHang Zhu
2012-10-25 1:48 ` Ni zhan Chen
2012-10-25 1:48 ` Ni zhan Chen
2012-10-25 1:50 ` Dave Chinner
2012-10-25 1:50 ` Dave Chinner
2012-10-25 2:04 ` YingHang Zhu
2012-10-25 2:04 ` YingHang Zhu
2012-10-25 2:12 ` Ni zhan Chen
2012-10-25 2:12 ` Ni zhan Chen
2012-10-25 2:31 ` YingHang Zhu
2012-10-25 2:31 ` YingHang Zhu
2012-10-25 2:58 ` Fengguang Wu
2012-10-25 2:58 ` Fengguang Wu
2012-10-25 3:12 ` YingHang Zhu
2012-10-25 3:12 ` YingHang Zhu
2012-10-26 0:25 ` Dave Chinner
2012-10-26 0:25 ` Dave Chinner
2012-10-26 1:27 ` Fengguang Wu
2012-10-26 1:27 ` Fengguang Wu
2012-10-26 2:30 ` Ni zhan Chen
2012-10-26 2:30 ` Ni zhan Chen
2012-10-26 3:28 ` YingHang Zhu
2012-10-26 3:28 ` YingHang Zhu
2012-10-26 3:51 ` Ni zhan Chen
2012-10-26 3:51 ` Ni zhan Chen
2012-10-26 4:35 ` YingHang Zhu
2012-10-26 4:35 ` YingHang Zhu
2012-10-26 6:58 ` Fengguang Wu
2012-10-26 6:58 ` Fengguang Wu
2012-10-26 7:03 ` Ni zhan Chen
2012-10-26 7:03 ` Ni zhan Chen
2012-10-26 7:09 ` Fengguang Wu
2012-10-26 7:09 ` Fengguang Wu
2012-10-26 7:19 ` Ni zhan Chen
2012-10-26 7:19 ` Ni zhan Chen
2012-10-26 7:36 ` Fengguang Wu
2012-10-26 7:36 ` Fengguang Wu
2012-10-26 7:47 ` Ni zhan Chen
2012-10-26 7:47 ` Ni zhan Chen
2012-10-26 8:02 ` Fengguang Wu
2012-10-26 8:02 ` Fengguang Wu
2012-10-26 8:08 ` Ni zhan Chen
2012-10-26 8:08 ` Ni zhan Chen
2012-10-26 8:13 ` YingHang Zhu
2012-10-26 8:13 ` YingHang Zhu
2012-10-26 2:25 ` Ni zhan Chen
2012-10-26 2:25 ` Ni zhan Chen
2012-10-26 3:38 ` YingHang Zhu
2012-10-26 3:38 ` YingHang Zhu
2012-10-26 3:55 ` Fengguang Wu
2012-10-26 3:55 ` Fengguang Wu
2012-10-26 5:00 ` YingHang Zhu
2012-10-26 5:00 ` YingHang Zhu
2012-10-25 2:38 ` Fengguang Wu [this message]
2012-10-25 2:38 ` Fengguang Wu
2012-10-25 3:08 ` YingHang Zhu
2012-10-25 3:08 ` YingHang Zhu
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