Disk IO scheduling in guest kernel slow


If I perform certain IO operations (such as deleting files) all other io operations nearly starve.

While deleting a 1gb file on the background, listing home directory files, ls ~ takes 10-15 seconds to complete:


create a file:

% dd if=/dev/zero of=testfile bs=1024M count=1

delete it on the background:

% rm testfile&

time ls of ~ (32 items on ~, mostly folders)

% time ls

ls -F --color=always 0.00s user 0.00s system 0% cpu 14.071 total

Is this typical?

Is there another disk IO scheduler available for install as a kernel module?

4 Replies

Just out of curiosity, have you tried nicing the rm job and/or running strace on the rm and/or the ls commands?

Seeing if there is a particular system call that is a bottleneck may provide useful information.

(Disclaimer: I am NOT an employee of Linode)


if I nice and ionice it seems to help a little, but the rm still takes ages.

ie: sudo nice -n 15 ionice -c3 rm foo

mwalling: xen

@achille Have you tried running the rm under strace yet?


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