virt-install and virt-manager both default to explicitly setting
"io='native'" in the disk "driver" tag. virsh, however, does not and also
does not provide an option to specify that setting at all. As a result,
disks use a different IO mechanism (the default, "threads") when attached
post-setup using virsh. Adding this option allows users to keep disk
performance consistent for disks attached at install, and those attached
afterward.
---
tools/virsh-domain.c | 14 +++++++++++---
tools/virsh.pod | 3 ++-
2 files changed, 13 insertions(+), 4 deletions(-)
diff --git a/tools/virsh-domain.c b/tools/virsh-domain.c
index 0d19d0e..5c42021 100644
--- a/tools/virsh-domain.c
+++ b/tools/virsh-domain.c
@@ -267,6 +267,10 @@ static const vshCmdOptDef opts_attach_disk[] = {
.type = VSH_OT_STRING,
.help = N_("cache mode of disk device")
},
+ {.name = "io",
+ .type = VSH_OT_STRING,
+ .help = N_("io policy of disk device")
+ },
{.name = "type",
.type = VSH_OT_STRING,
.help = N_("target device type")
@@ -504,8 +508,9 @@ cmdAttachDisk(vshControl *ctl, const vshCmd *cmd)
virDomainPtr dom = NULL;
const char *source = NULL, *target = NULL, *driver = NULL,
*subdriver = NULL, *type = NULL, *mode = NULL,
- *iothread = NULL, *cache = NULL, *serial = NULL,
- *straddr = NULL, *wwn = NULL, *targetbus = NULL;
+ *iothread = NULL, *cache = NULL, *io = NULL,
+ *serial = NULL, *straddr = NULL, *wwn = NULL,
+ *targetbus = NULL;
struct DiskAddress diskAddr;
bool isFile = false, functionReturn = false;
int ret;
@@ -537,6 +542,7 @@ cmdAttachDisk(vshControl *ctl, const vshCmd *cmd)
vshCommandOptStringReq(ctl, cmd, "mode", &mode) < 0 ||
vshCommandOptStringReq(ctl, cmd, "iothread", &iothread) < 0 ||
vshCommandOptStringReq(ctl, cmd, "cache", &cache) < 0 ||
+ vshCommandOptStringReq(ctl, cmd, "io", &io) < 0 ||
vshCommandOptStringReq(ctl, cmd, "serial", &serial) < 0 ||
vshCommandOptStringReq(ctl, cmd, "wwn", &wwn) < 0 ||
vshCommandOptStringReq(ctl, cmd, "address", &straddr) < 0 ||
@@ -579,7 +585,7 @@ cmdAttachDisk(vshControl *ctl, const vshCmd *cmd)
virBufferAddLit(&buf, ">\n");
virBufferAdjustIndent(&buf, 2);
- if (driver || subdriver || iothread || cache) {
+ if (driver || subdriver || iothread || cache || io) {
virBufferAddLit(&buf, "<driver");
if (driver)
@@ -590,6 +596,8 @@ cmdAttachDisk(vshControl *ctl, const vshCmd *cmd)
virBufferAsprintf(&buf, " iothread='%s'", iothread);
if (cache)
virBufferAsprintf(&buf, " cache='%s'", cache);
+ if (io)
+ virBufferAsprintf(&buf, " io='%s'", io);
virBufferAddLit(&buf, "/>\n");
}
diff --git a/tools/virsh.pod b/tools/virsh.pod
index 727acf6..f46fb4a 100644
--- a/tools/virsh.pod
+++ b/tools/virsh.pod
@@ -2838,7 +2838,7 @@ expected.
=item B<attach-disk> I<domain> I<source> I<target> [[[I<--live>] [I<--config>]
| [I<--current>]] | [I<--persistent>]] [I<--targetbus bus>] [I<--driver
driver>] [I<--subdriver subdriver>] [I<--iothread iothread>]
-[I<--cache cache>] [I<--type type>]
+[I<--cache cache>] [I<--io io>] [I<--type type>]
[I<--mode mode>] [I<--sourcetype sourcetype>] [I<--serial serial>] [I<--wwn
wwn>] [I<--rawio>] [I<--address address>] [I<--multifunction>] [I<--print-xml>]
@@ -2865,6 +2865,7 @@ I<mode> can specify the two specific mode I<readonly> or I<shareable>.
I<sourcetype> can indicate the type of source (block|file)
I<cache> can be one of "default", "none", "writethrough", "writeback",
"directsync" or "unsafe".
+I<io> controls specific policies on I/O; qemu guests support "threads" and "native".
I<iothread> is the number within the range of domain IOThreads to which
this disk may be attached (QEMU only).
I<serial> is the serial of disk device. I<wwn> is the wwn of disk device.
--
2.9.3
--
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