From: Wu Fengguang <fengguang.wu@intel.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Andi Kleen <andi@firstfloor.org>, Rik van Riel <riel@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Wu Fengguang <fengguang.wu@intel.com>
Cc: Linux Memory Management List <linux-mm@kvack.org>,
<linux-fsdevel@vger.kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>
Subject: [PATCH 09/10] readahead: dont do start-of-file readahead after lseek()
Date: Mon, 19 Dec 2011 18:23:17 +0800 [thread overview]
Message-ID: <20111219102357.682742832@intel.com> (raw)
In-Reply-To: 20111219102308.488847921@intel.com
[-- Attachment #1: readahead-lseek.patch --]
[-- Type: text/plain, Size: 2553 bytes --]
Some applications (eg. blkid, id3tool etc.) seek around the file
to get information. For example, blkid does
seek to 0
read 1024
seek to 1536
read 16384
The start-of-file readahead heuristic is wrong for them, whose
access pattern can be identified by lseek() calls.
So test-and-set a READAHEAD_LSEEK flag on lseek() and don't
do start-of-file readahead on seeing it. Proposed by Linus.
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
---
fs/read_write.c | 3 +++
include/linux/fs.h | 1 +
mm/readahead.c | 4 ++++
3 files changed, 8 insertions(+)
--- linux-next.orig/mm/readahead.c 2011-12-19 16:09:45.000000000 +0800
+++ linux-next/mm/readahead.c 2011-12-19 16:10:06.000000000 +0800
@@ -476,6 +476,7 @@ unsigned long ra_submit(struct file_ra_s
ra->pattern, ra->start, ra->size, ra->async_size,
actual);
+ ra->lseek = 0;
ra->for_mmap = 0;
ra->for_metadata = 0;
return actual;
@@ -627,6 +628,8 @@ ondemand_readahead(struct address_space
* start of file
*/
if (!offset) {
+ if (ra->lseek && req_size < max)
+ goto random_read;
ra->pattern = RA_PATTERN_INITIAL;
goto initial_readahead;
}
@@ -712,6 +715,7 @@ ondemand_readahead(struct address_space
if (try_context_readahead(mapping, ra, offset, req_size, max))
goto readit;
+random_read:
/*
* standalone, small random read
*/
--- linux-next.orig/fs/read_write.c 2011-12-18 14:06:28.000000000 +0800
+++ linux-next/fs/read_write.c 2011-12-19 16:09:45.000000000 +0800
@@ -47,6 +47,9 @@ static loff_t lseek_execute(struct file
file->f_pos = offset;
file->f_version = 0;
}
+
+ file->f_ra.lseek = 1;
+
return offset;
}
--- linux-next.orig/include/linux/fs.h 2011-12-19 16:09:45.000000000 +0800
+++ linux-next/include/linux/fs.h 2011-12-19 16:09:45.000000000 +0800
@@ -951,6 +951,7 @@ struct file_ra_state {
u8 pattern; /* one of RA_PATTERN_* */
unsigned int for_mmap:1; /* readahead for mmap accesses */
unsigned int for_metadata:1; /* readahead for meta data */
+ unsigned int lseek:1; /* this read has a leading lseek */
loff_t prev_pos; /* Cache last read() position */
};
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
WARNING: multiple messages have this Message-ID (diff)
From: Wu Fengguang <fengguang.wu@intel.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Andi Kleen <andi@firstfloor.org>, Rik van Riel <riel@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Wu Fengguang <fengguang.wu@intel.com>,
Linux Memory Management List <linux-mm@kvack.org>,
linux-fsdevel@vger.kernel.org,
LKML <linux-kernel@vger.kernel.org>
Subject: [PATCH 09/10] readahead: dont do start-of-file readahead after lseek()
Date: Mon, 19 Dec 2011 18:23:17 +0800 [thread overview]
Message-ID: <20111219102357.682742832@intel.com> (raw)
In-Reply-To: 20111219102308.488847921@intel.com
[-- Attachment #1: readahead-lseek.patch --]
[-- Type: text/plain, Size: 2553 bytes --]
Some applications (eg. blkid, id3tool etc.) seek around the file
to get information. For example, blkid does
seek to 0
read 1024
seek to 1536
read 16384
The start-of-file readahead heuristic is wrong for them, whose
access pattern can be identified by lseek() calls.
So test-and-set a READAHEAD_LSEEK flag on lseek() and don't
do start-of-file readahead on seeing it. Proposed by Linus.
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
---
fs/read_write.c | 3 +++
include/linux/fs.h | 1 +
mm/readahead.c | 4 ++++
3 files changed, 8 insertions(+)
--- linux-next.orig/mm/readahead.c 2011-12-19 16:09:45.000000000 +0800
+++ linux-next/mm/readahead.c 2011-12-19 16:10:06.000000000 +0800
@@ -476,6 +476,7 @@ unsigned long ra_submit(struct file_ra_s
ra->pattern, ra->start, ra->size, ra->async_size,
actual);
+ ra->lseek = 0;
ra->for_mmap = 0;
ra->for_metadata = 0;
return actual;
@@ -627,6 +628,8 @@ ondemand_readahead(struct address_space
* start of file
*/
if (!offset) {
+ if (ra->lseek && req_size < max)
+ goto random_read;
ra->pattern = RA_PATTERN_INITIAL;
goto initial_readahead;
}
@@ -712,6 +715,7 @@ ondemand_readahead(struct address_space
if (try_context_readahead(mapping, ra, offset, req_size, max))
goto readit;
+random_read:
/*
* standalone, small random read
*/
--- linux-next.orig/fs/read_write.c 2011-12-18 14:06:28.000000000 +0800
+++ linux-next/fs/read_write.c 2011-12-19 16:09:45.000000000 +0800
@@ -47,6 +47,9 @@ static loff_t lseek_execute(struct file
file->f_pos = offset;
file->f_version = 0;
}
+
+ file->f_ra.lseek = 1;
+
return offset;
}
--- linux-next.orig/include/linux/fs.h 2011-12-19 16:09:45.000000000 +0800
+++ linux-next/include/linux/fs.h 2011-12-19 16:09:45.000000000 +0800
@@ -951,6 +951,7 @@ struct file_ra_state {
u8 pattern; /* one of RA_PATTERN_* */
unsigned int for_mmap:1; /* readahead for mmap accesses */
unsigned int for_metadata:1; /* readahead for meta data */
+ unsigned int lseek:1; /* this read has a leading lseek */
loff_t prev_pos; /* Cache last read() position */
};
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
WARNING: multiple messages have this Message-ID (diff)
From: Wu Fengguang <fengguang.wu@intel.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Andi Kleen <andi@firstfloor.org>, Rik van Riel <riel@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Wu Fengguang <fengguang.wu@intel.com>
Cc: Linux Memory Management List <linux-mm@kvack.org>,
<linux-fsdevel@vger.kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>
Subject: [PATCH 09/10] readahead: dont do start-of-file readahead after lseek()
Date: Mon, 19 Dec 2011 18:23:17 +0800 [thread overview]
Message-ID: <20111219102357.682742832@intel.com> (raw)
In-Reply-To: 20111219102308.488847921@intel.com
[-- Attachment #1: readahead-lseek.patch --]
[-- Type: text/plain, Size: 2250 bytes --]
Some applications (eg. blkid, id3tool etc.) seek around the file
to get information. For example, blkid does
seek to 0
read 1024
seek to 1536
read 16384
The start-of-file readahead heuristic is wrong for them, whose
access pattern can be identified by lseek() calls.
So test-and-set a READAHEAD_LSEEK flag on lseek() and don't
do start-of-file readahead on seeing it. Proposed by Linus.
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
---
fs/read_write.c | 3 +++
include/linux/fs.h | 1 +
mm/readahead.c | 4 ++++
3 files changed, 8 insertions(+)
--- linux-next.orig/mm/readahead.c 2011-12-19 16:09:45.000000000 +0800
+++ linux-next/mm/readahead.c 2011-12-19 16:10:06.000000000 +0800
@@ -476,6 +476,7 @@ unsigned long ra_submit(struct file_ra_s
ra->pattern, ra->start, ra->size, ra->async_size,
actual);
+ ra->lseek = 0;
ra->for_mmap = 0;
ra->for_metadata = 0;
return actual;
@@ -627,6 +628,8 @@ ondemand_readahead(struct address_space
* start of file
*/
if (!offset) {
+ if (ra->lseek && req_size < max)
+ goto random_read;
ra->pattern = RA_PATTERN_INITIAL;
goto initial_readahead;
}
@@ -712,6 +715,7 @@ ondemand_readahead(struct address_space
if (try_context_readahead(mapping, ra, offset, req_size, max))
goto readit;
+random_read:
/*
* standalone, small random read
*/
--- linux-next.orig/fs/read_write.c 2011-12-18 14:06:28.000000000 +0800
+++ linux-next/fs/read_write.c 2011-12-19 16:09:45.000000000 +0800
@@ -47,6 +47,9 @@ static loff_t lseek_execute(struct file
file->f_pos = offset;
file->f_version = 0;
}
+
+ file->f_ra.lseek = 1;
+
return offset;
}
--- linux-next.orig/include/linux/fs.h 2011-12-19 16:09:45.000000000 +0800
+++ linux-next/include/linux/fs.h 2011-12-19 16:09:45.000000000 +0800
@@ -951,6 +951,7 @@ struct file_ra_state {
u8 pattern; /* one of RA_PATTERN_* */
unsigned int for_mmap:1; /* readahead for mmap accesses */
unsigned int for_metadata:1; /* readahead for meta data */
+ unsigned int lseek:1; /* this read has a leading lseek */
loff_t prev_pos; /* Cache last read() position */
};
next prev parent reply other threads:[~2011-12-19 10:23 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-19 10:23 [PATCH 00/10] readahead stats/tracing, backwards prefetching and more (v3) Wu Fengguang
2011-12-19 10:23 ` Wu Fengguang
2011-12-19 10:23 ` Wu Fengguang
2011-12-19 10:23 ` [PATCH 01/10] block: limit default readahead size for small devices Wu Fengguang
2011-12-19 10:23 ` Wu Fengguang
2011-12-19 10:23 ` [PATCH 02/10] readahead: make context readahead more conservative Wu Fengguang
2011-12-19 10:23 ` Wu Fengguang
2011-12-19 10:23 ` Wu Fengguang
2011-12-19 10:23 ` [PATCH 03/10] readahead: record readahead patterns Wu Fengguang
2011-12-19 10:23 ` Wu Fengguang
2011-12-19 10:23 ` Wu Fengguang
2011-12-19 10:23 ` [PATCH 04/10] readahead: tag mmap page fault call sites Wu Fengguang
2011-12-19 10:23 ` Wu Fengguang
2011-12-19 10:23 ` Wu Fengguang
2011-12-19 10:23 ` [PATCH 05/10] readahead: tag metadata " Wu Fengguang
2011-12-19 10:23 ` Wu Fengguang
2011-12-19 10:23 ` Wu Fengguang
2011-12-19 10:23 ` [PATCH 06/10] readahead: add vfs/readahead tracing event Wu Fengguang
2011-12-19 10:23 ` Wu Fengguang
2011-12-19 10:23 ` Wu Fengguang
2011-12-19 10:23 ` [PATCH 07/10] readahead: add /debug/readahead/stats Wu Fengguang
2011-12-19 10:23 ` Wu Fengguang
2011-12-19 10:23 ` Wu Fengguang
2011-12-23 12:59 ` [PATCH 07/10 v2] " Wu Fengguang
2011-12-23 12:59 ` Wu Fengguang
2011-12-23 13:48 ` Jan Kara
2011-12-23 13:48 ` Jan Kara
2011-12-19 10:23 ` [PATCH 08/10] readahead: basic support for backwards prefetching Wu Fengguang
2011-12-19 10:23 ` Wu Fengguang
2011-12-19 10:23 ` Wu Fengguang
2011-12-19 10:23 ` Wu Fengguang [this message]
2011-12-19 10:23 ` [PATCH 09/10] readahead: dont do start-of-file readahead after lseek() Wu Fengguang
2011-12-19 10:23 ` Wu Fengguang
2011-12-19 10:23 ` [PATCH 10/10] readahead: snap readahead request to EOF Wu Fengguang
2011-12-19 10:23 ` Wu Fengguang
2011-12-19 10:23 ` Wu Fengguang
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=20111219102357.682742832@intel.com \
--to=fengguang.wu@intel.com \
--cc=akpm@linux-foundation.org \
--cc=andi@firstfloor.org \
--cc=riel@redhat.com \
--cc=torvalds@linux-foundation.org \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.