From: Fengguang Wu <fengguang.wu@intel.com>
To: Raghavendra D Prabhu <raghu.prabhu13@gmail.com>
Cc: linux-mm@kvack.org, viro@zeniv.linux.org.uk, akpm@linux-foundation.org
Subject: Re: Re: [PATCH 2/5] mm/readahead: Change the condition for SetPageReadahead
Date: Fri, 28 Sep 2012 19:56:23 +0800 [thread overview]
Message-ID: <20120928115623.GB1525@localhost> (raw)
In-Reply-To: <20120926012900.GA36532@Archie>
On Wed, Sep 26, 2012 at 06:59:00AM +0530, Raghavendra D Prabhu wrote:
> Hi,
>
>
> * On Sat, Sep 22, 2012 at 08:49:20PM +0800, Fengguang Wu <fengguang.wu@intel.com> wrote:
> >On Sat, Sep 22, 2012 at 04:03:11PM +0530, raghu.prabhu13@gmail.com wrote:
> >>From: Raghavendra D Prabhu <rprabhu@wnohang.net>
> >>
> >>If page lookup from radix_tree_lookup is successful and its index page_idx ==
> >>nr_to_read - lookahead_size, then SetPageReadahead never gets called, so this
> >>fixes that.
> >
> >NAK. Sorry. It's actually an intentional behavior, so that for the
> >common cases of many cached files that are accessed frequently, no
> >PG_readahead will be set at all to pointlessly trap into the readahead
> >routines once and again.
>
> ACK, thanks for explaining that. However, regarding this, I would
> like to know if the implications of the patch
> 51daa88ebd8e0d437289f589af29d4b39379ea76 will still apply if
> PG_readahead is not set.
Would you elaborate the implication and the possible problematic case?
Thanks,
Fengguang
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next prev parent reply other threads:[~2012-09-28 11:56 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-22 10:33 [PATCH 0/5] Readahead fixes / improvements raghu.prabhu13
[not found] ` <cover.1348309711.git.rprabhu@wnohang.net>
2012-09-22 10:33 ` [PATCH 1/5] mm/readahead: Check return value of read_pages raghu.prabhu13
2012-09-22 12:43 ` Fengguang Wu
2012-09-26 1:25 ` Raghavendra D Prabhu
2012-09-28 11:54 ` Fengguang Wu
2012-10-16 17:47 ` Raghavendra D Prabhu
2012-10-17 2:53 ` Fengguang Wu
2012-09-22 10:33 ` [PATCH 2/5] mm/readahead: Change the condition for SetPageReadahead raghu.prabhu13
2012-09-22 12:49 ` Fengguang Wu
2012-09-26 1:29 ` Raghavendra D Prabhu
2012-09-28 11:56 ` Fengguang Wu [this message]
2012-10-16 17:42 ` Raghavendra D Prabhu
2012-10-17 2:34 ` Fengguang Wu
2012-09-22 10:33 ` [PATCH 3/5] Remove file_ra_state from arguments of count_history_pages raghu.prabhu13
2012-09-22 12:40 ` Fengguang Wu
2012-10-16 18:21 ` Raghavendra D Prabhu
2012-10-17 3:15 ` Fengguang Wu
2012-09-22 10:33 ` [PATCH 4/5] Move the check for ra_pages after VM_SequentialReadHint() raghu.prabhu13
2012-09-22 12:42 ` Fengguang Wu
2012-09-26 1:39 ` Raghavendra D Prabhu
2012-10-16 18:15 ` Raghavendra D Prabhu
2012-10-17 3:13 ` Fengguang Wu
2012-09-22 10:33 ` [PATCH 5/5] mm/readahead: Use find_get_pages instead of radix_tree_lookup raghu.prabhu13
2012-09-22 13:15 ` Fengguang Wu
2012-09-26 2:58 ` Raghavendra D Prabhu
2012-09-28 12:18 ` Fengguang Wu
2012-10-16 16:59 ` Raghavendra D Prabhu
2012-10-17 2:12 ` Fengguang Wu
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