Messages in this thread | | | Date | Wed, 12 Dec 2001 16:11:02 -0800 | From | "H . J . Lu" <> | Subject | Re: Slow Disk I/O with QPS M3 80GB HD |
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On Thu, Dec 13, 2001 at 12:49:33AM +0100, Andrea Arcangeli wrote: > 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
I applied all the way to 40_blkdev-pagecache-17 in 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.
That is why I said it was strange.
> > Can you try to take those cp under strace timestamp and see what's the > syscall that blocks?
It blocks on read.
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