diff options
| author | Paolo Bonzini <pbonzini@redhat.com> | 2013-12-20 15:54:27 +0100 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2013-12-22 14:59:33 +0100 |
| commit | 8a1bd2973ed5f99a3c37c9afdff823c4a22152b1 (patch) | |
| tree | 5cb0243ab1005d00f037334e294f7adfa87a7b78 /hw/misc/lm32_sys.c | |
| parent | 8b9dfe9098d91e06a3dd6376624307fe5fa13be8 (diff) | |
| download | focaccia-qemu-8a1bd2973ed5f99a3c37c9afdff823c4a22152b1.tar.gz focaccia-qemu-8a1bd2973ed5f99a3c37c9afdff823c4a22152b1.zip | |
scsi-disk: add UNMAP limits to block limits VPD page
Linux prefers WRITE SAME to UNMAP if the limits are zero, and WRITE SAME does not discard anything unless the device can guarantee that the resulting block is zero. Setting the maximum unmap block and descriptor counts to non-zero makes Linux choose UNMAP and fixes thin provisioning on glusterfs. While the maximum unmap block count can have some effect on performance, the (suggested) maximum number of descriptors is not particularly important so I didn't add a customization option. SCSI drivers are used to online firmware updates so I'm not yet adding versioning support for SCSI, but we're probably getting close to the point when it's worth thinking about it. Reported-by: Bharata B Rao <bharata@linux.vnet.ibm.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'hw/misc/lm32_sys.c')
0 files changed, 0 insertions, 0 deletions