On Friday July 28, ssmeenk@xxxxxxxxxxxx wrote:
> Quoting Neil Brown (neilb@xxxxxxx):
>
> > Precisely what evidence do you have?
>
> I had a nicer strace. With the 30 seconds fsync() call in it. This one
> only took 4 seconds, but that's because only two of us were trying to
> generate enough disk IO to make it happen ;)
>
> Look here, the read(0, "\r", 250) = 1 is the moment i hit <CR> on the :w
> command to vim.
>
> 13:28:06.183890 open(".js_gen.pl.swp", O_RDWR|O_CREAT|O_EXCL, 0600) = 4
>
> 13:28:07.011671 select(1, [0], NULL, [0], {0, 0}) = 0 (Timeout)
> *********
> 13:28:07.011717 fsync(4) = 0
> 13:28:12.748252 open("js_gen.pl", O_WRONLY|O_CREAT|O_TRUNC, 0770) = 3
> *********
> 13:28:12.748427 write(3, "#!/usr/bin/perl -w\nuse strict;\nu"..., 2189) = 2189
> 13:28:12.748506 fsync(3) = 0
> 13:28:13.006702 close(3) = 0
Yes, it's weird. The sync of the .swp file takes a lot longer than
the fsync of the actual file you are saving....
I have this theory that there might be some odd interaction between md
and the drive scheduler.
Can you try
echo cfq > /sys/block/sdb/queue/scheduler
echo cfq > /sys/block/sdc/queue/scheduler
and try again.
Maybe also try 'deadline' instead of 'cfq'.
Let me know what the results are.
Thanks,
NeilBrown
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