2005-04-16 15:20:36 -07:00
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2008-10-03 17:32:43 -04:00
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2005-04-16 15:20:36 -07:00
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2005-06-23 22:05:26 -07:00
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2005-04-16 15:20:36 -07:00
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2005-09-09 13:01:31 -07:00
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2005-04-16 15:20:36 -07:00
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2007-10-16 23:30:46 -07:00
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2005-04-16 15:20:36 -07:00
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2008-04-21 22:45:55 +00:00
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2005-04-16 15:20:36 -07:00
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2008-04-28 02:16:02 -07:00
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2005-04-16 15:20:36 -07:00
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2008-04-28 02:16:02 -07:00
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2005-04-16 15:20:36 -07:00
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2008-04-28 02:16:01 -07:00
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2005-04-16 15:20:36 -07:00
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2008-04-21 22:45:55 +00:00
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2005-04-16 15:20:36 -07:00
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2007-10-16 23:30:46 -07:00
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2005-04-16 15:20:36 -07:00
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2008-04-28 02:16:02 -07:00
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2005-04-16 15:20:36 -07:00
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2007-10-16 23:30:46 -07:00
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2005-04-16 15:20:36 -07:00
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2007-10-16 23:30:46 -07:00
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2005-04-16 15:20:36 -07:00
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2007-10-16 23:30:46 -07:00
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2005-04-16 15:20:36 -07:00
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2007-10-16 23:30:46 -07:00
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2005-04-16 15:20:36 -07:00
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2007-10-16 23:30:46 -07:00
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2005-04-16 15:20:36 -07:00
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2007-10-16 23:30:46 -07:00
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2005-04-16 15:20:36 -07:00
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2007-10-16 23:30:46 -07:00
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2005-04-16 15:20:36 -07:00
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2007-10-16 23:30:46 -07:00
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2005-04-16 15:20:36 -07:00
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2007-10-16 23:30:46 -07:00
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2005-04-16 15:20:36 -07:00
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2007-10-16 23:30:46 -07:00
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2005-04-16 15:20:36 -07:00
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2007-10-16 23:30:46 -07:00
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2006-03-26 01:38:02 -08:00
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2006-06-28 04:26:44 -07:00
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2007-10-16 01:25:04 -07:00
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2006-02-01 03:05:41 -08:00
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vfs: pagecache usage optimization for pagesize!=blocksize
When we read some part of a file through pagecache, if there is a
pagecache of corresponding index but this page is not uptodate, read IO
is issued and this page will be uptodate.
I think this is good for pagesize == blocksize environment but there is
room for improvement on pagesize != blocksize environment. Because in
this case a page can have multiple buffers and even if a page is not
uptodate, some buffers can be uptodate.
So I suggest that when all buffers which correspond to a part of a file
that we want to read are uptodate, use this pagecache and copy data from
this pagecache to user buffer even if a page is not uptodate. This can
reduce read IO and improve system throughput.
I wrote a benchmark program and got result number with this program.
This benchmark do:
1: mount and open a test file.
2: create a 512MB file.
3: close a file and umount.
4: mount and again open a test file.
5: pwrite randomly 300000 times on a test file. offset is aligned
by IO size(1024bytes).
6: measure time of preading randomly 100000 times on a test file.
The result was:
2.6.26
330 sec
2.6.26-patched
226 sec
Arch:i386
Filesystem:ext3
Blocksize:1024 bytes
Memory: 1GB
On ext3/4, a file is written through buffer/block. So random read/write
mixed workloads or random read after random write workloads are optimized
with this patch under pagesize != blocksize environment. This test result
showed this.
The benchmark program is as follows:
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <time.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mount.h>
#define LEN 1024
#define LOOP 1024*512 /* 512MB */
main(void)
{
unsigned long i, offset, filesize;
int fd;
char buf[LEN];
time_t t1, t2;
if (mount("/dev/sda1", "/root/test1/", "ext3", 0, 0) < 0) {
perror("cannot mount\n");
exit(1);
}
memset(buf, 0, LEN);
fd = open("/root/test1/testfile", O_CREAT|O_RDWR|O_TRUNC);
if (fd < 0) {
perror("cannot open file\n");
exit(1);
}
for (i = 0; i < LOOP; i++)
write(fd, buf, LEN);
close(fd);
if (umount("/root/test1/") < 0) {
perror("cannot umount\n");
exit(1);
}
if (mount("/dev/sda1", "/root/test1/", "ext3", 0, 0) < 0) {
perror("cannot mount\n");
exit(1);
}
fd = open("/root/test1/testfile", O_RDWR);
if (fd < 0) {
perror("cannot open file\n");
exit(1);
}
filesize = LEN * LOOP;
for (i = 0; i < 300000; i++){
offset = (random() % filesize) & (~(LEN - 1));
pwrite(fd, buf, LEN, offset);
}
printf("start test\n");
time(&t1);
for (i = 0; i < 100000; i++){
offset = (random() % filesize) & (~(LEN - 1));
pread(fd, buf, LEN, offset);
}
time(&t2);
printf("%ld sec\n", t2-t1);
close(fd);
if (umount("/root/test1/") < 0) {
perror("cannot umount\n");
exit(1);
}
}
Signed-off-by: Hisashi Hifumi <hifumi.hisashi@oss.ntt.co.jp>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Jan Kara <jack@ucw.cz>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-28 15:46:36 -07:00
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2005-06-23 22:05:26 -07:00
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2008-04-28 02:13:02 -07:00
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2005-06-23 22:05:26 -07:00
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2006-06-28 04:26:44 -07:00
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2007-10-16 01:25:25 -07:00
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2005-04-16 15:20:36 -07:00
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2006-02-01 03:05:41 -08:00
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2005-04-16 15:20:36 -07:00
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2007-10-16 23:30:46 -07:00
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2005-04-16 15:20:36 -07:00
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2007-10-16 23:30:46 -07:00
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2005-04-16 15:20:36 -07:00
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2005-06-23 22:05:26 -07:00
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2007-10-16 01:25:25 -07:00
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2005-04-16 15:20:36 -07:00
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2007-10-16 23:30:46 -07:00
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2005-04-16 15:20:36 -07:00
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2007-10-16 23:30:46 -07:00
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2005-04-16 15:20:36 -07:00
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2007-10-16 23:26:30 -07:00
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2005-04-16 15:20:36 -07:00
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2007-05-08 00:31:04 -07:00
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2008-02-07 00:15:35 -08:00
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2005-04-16 15:20:36 -07:00
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2008-02-07 00:15:35 -08:00
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2005-04-16 15:20:36 -07:00
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2008-02-07 00:15:35 -08:00
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2005-04-16 15:20:36 -07:00
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2008-02-07 00:15:35 -08:00
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2005-04-16 15:20:36 -07:00
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2007-10-16 23:30:46 -07:00
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2008-02-07 00:15:35 -08:00
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2005-04-16 15:20:36 -07:00
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2008-02-07 00:15:35 -08:00
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2005-04-16 15:20:36 -07:00
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ext2/3/4: fix file date underflow on ext2 3 filesystems on 64 bit systems
Taken from http://bugzilla.kernel.org/show_bug.cgi?id=5079
signed long ranges from -2.147.483.648 to 2.147.483.647 on x86 32bit
10000011110110100100111110111101 .. -2,082,844,739
10000011110110100100111110111101 .. 2,212,122,557 <- this currently gets
stored on the disk but when converting it to a 64bit signed long value it loses
its sign and becomes positive.
Cc: Andreas Dilger <adilger@dilger.ca>
Cc: <linux-ext4@vger.kernel.org>
Andreas says:
This patch is now treating timestamps with the high bit set as negative
times (before Jan 1, 1970). This means we lose 1/2 of the possible range
of timestamps (lopping off 68 years before unix timestamp overflow -
now only 30 years away :-) to handle the extremely rare case of setting
timestamps into the distant past.
If we are only interested in fixing the underflow case, we could just
limit the values to 0 instead of storing negative values. At worst this
will skew the timestamp by a few hours for timezones in the far east
(files would still show Jan 1, 1970 in "ls -l" output).
That said, it seems 32-bit systems (mine at least) allow files to be set
into the past (01/01/1907 works fine) so it seems this patch is bringing
the x86_64 behaviour into sync with other kernels.
On the plus side, we have a patch that is ready to add nanosecond timestamps
to ext3 and as an added bonus adds 2 high bits to the on-disk timestamp so
this extends the maximum date to 2242.
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 00:23:39 -07:00
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2005-04-16 15:20:36 -07:00
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2008-02-07 00:15:35 -08:00
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2005-04-16 15:20:36 -07:00
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2005-06-23 22:05:26 -07:00
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2005-04-16 15:20:36 -07:00
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2005-06-23 22:05:26 -07:00
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2005-04-16 15:20:36 -07:00
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2005-06-23 22:05:26 -07:00
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2005-04-16 15:20:36 -07:00
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2008-02-07 00:15:35 -08:00
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2005-04-16 15:20:36 -07:00
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2008-02-07 00:15:35 -08:00
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2005-04-16 15:20:36 -07:00
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2007-05-08 00:31:04 -07:00
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2005-04-16 15:20:36 -07:00
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