[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] fstrim & upstream kernel not working
From: |
Richard W.M. Jones |
Subject: |
[Qemu-devel] fstrim & upstream kernel not working |
Date: |
Thu, 13 Mar 2014 21:49:35 +0000 |
User-agent: |
Mutt/1.5.20 (2009-12-10) |
I got fstrim happily working in Fedora 20, but it's not working with
the upstream kernel. The message is:
fstrim -v /sysroot/
[ 45.541339] sda: WRITE SAME failed. Manually zeroing.
/sysroot/: 47.2 MiB (49466368 bytes) trimmed
While this isn't technically an error, it of course doesn't trim
anything. In fact the host disk grows after the fstrim.
A couple of questions:
- Is there any reason why virtio-scsi doesn't emulate WRITE SAME? It
seems pretty simple, and upstream kernels issue WRITE SAME when they
want to zero large areas of disk.
- Can you see where ext4 issues the zeroout/write same call? AFAICT
it is still issuing discards, but these are getting turned into
zeroout/write same by some sort of block layer magic that I can't
quite follow.
kernel: 3.14.0-0.rc6.git2.1.fc21
qemu: 1.7.0-5.fc21.x86_64
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming blog: http://rwmj.wordpress.com
Fedora now supports 80 OCaml packages (the OPEN alternative to F#)
- [Qemu-devel] fstrim & upstream kernel not working,
Richard W.M. Jones <=