Messages in this thread | | | Date | Thu, 10 May 2012 10:24:28 +0200 | Subject | Re: Big I/O latencies, except when iotop is hooked | From | Felipe Contreras <> |
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On Wed, May 9, 2012 at 7:56 PM, Arnd Bergmann <arnd@arndb.de> wrote:
> The first thing you should check is whether the partitions are > properly aligned, using 'fdisk -l -u /dev/sdX'.
I aligned it to 4MiB, it doesn't make much of a difference.
> Of course none of this will tell you why iotop makes any difference.
After trying a bit more I can still see the problem with iotop, I could swear it happens much less often, but I can't really be sure now.
I tried with different io schedulers, and it seems cfq does better, I also tried different priorities, but the issue was still there.
I also tried to setup the crypto partition with align-payload, to no avail, and to get rid of crypto altogether. I also tried with multiple ext4 format options, but they seemed to make matters worst.
I finally tried on a normal disk device, and it works perfectly there (even with encryption); so the issue happens only on SSD/usb key.
Cheers.
-- Felipe Contreras
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