On Wed, 2004-03-31 at 17:49, Stephen C. Tweedie wrote:
> > I'd be happy to provide more information but so far I cannot decide
> > where to look... Should I learn to use "kernel profiling"?
>
> Sound like it. You've got two choices --- the simple "readprofile"
> (boot with profile=2), or set up an oprofile kernel. For complex
> user/kernel interactions oprofile can be really helpful, but for
> something that's simply stuck in the kernel, readprofile is fine.
OK, this is readprofile output of sync(1). To reproduce the situation,
I did a lot of copying of data and in parallel, setqouta for a few
thousands of group ids. After this kind of activity, sync becomes slow
(in my case it took a couple of minutes. It will take much more after
more activity).
$ readprofile -m /isolinux/System.map |sort -n|tail -20
11 zap_pte_range 0.0220
13 system_call 0.2321
14 do_wp_page 0.0182
19 __find_get_page 0.2375
35 __constant_memcpy 0.1287
35 ext3_group_sparse 0.1683
47 .text.lock.tty_io 0.1196
70 dqget 0.1326
76 .text.lock.inode 0.3028
89 do_page_fault 0.0668
97 .text.lock.namei 0.0820
105 .text.lock.read_write 0.9052
138 .text.lock.attr 2.1562
202 .text.lock.inode 0.3033
388 .text.lock.ioctl 10.7778
445 .text.lock.exit 1.5188
1283 default_idle 16.0375
2942 .text.lock.sched 7.8245
4414 vfs_quota_sync 11.0350
10775 total 0.0060
Does it help? Tell me what to do next.
Eugene
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