Messages in this thread | | | Date | Thu, 13 Dec 2001 00:49:33 +0100 | From | Andrea Arcangeli <> | Subject | Re: Slow Disk I/O with QPS M3 80GB HD |
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On Wed, Dec 12, 2001 at 03:38:06PM -0800, H . J . Lu wrote: > H.J. > ---- > 3 files on USB: > > # ls -l > total 5984 > -rwxr-xr-x 1 root root 1991481 Dec 8 21:44 dsc00002.jpg > -rwxr-xr-x 1 root root 2432127 Dec 8 23:54 dsc00005.jpg > -rwxr-xr-x 1 root root 1675563 Dec 8 23:59 dsc00009.jpg > > 1. 2.4.10-pre10 > > # time /bin/cp * /tmp/ > real 0m0.623s > user 0m0.000s > sys 0m0.100s > > 2. 2.4.10-pre10aa1 > > # time /bin/cp * /tmp/ > real 0m8.952s > user 0m0.000s > sys 0m0.190s > > > 3. 2.4.10-pre11 > > # time /bin/cp * /tmp/ > real 0m8.851s > user 0m0.000s > sys 0m0.170s
but the above have nothing to do with the blkdev-pagecache. Blkdev-pagecache can matter only with blkdev accesses, blkdev-pagecache cannot make any difference if the I/O passes through any fs (not via the block_dev layer) like in the above case.
Can you try to take those cp under strace timestamp and see what's the syscall that blocks?
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