4:07 p.m.
The libxl driver currently sets the disk backend to
LIBXL_DISK_BACKEND_TAP when <driver name='file'> is specified
in the <disk> config. qdisk should be prefered with this
configuration, otherwise existing configuration such as the
following, which worked with the old Xen driver, will not work
with the libxl driver
<disk type='file' device='cdrom'>
<driver name='file'/>
<source file='/path/to/some/iso'/>
<target dev='hdc' bus='ide'/>
<readonly/>
</disk>
In addition, tap performs poorly compared to qdisk.
Signed-off-by: Jim Fehlig <jfehlig(a)suse.com>
---
src/libxl/libxl_conf.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/libxl/libxl_conf.c b/src/libxl/libxl_conf.c
index fdbb522..4b6b5c0 100644
--- a/src/libxl/libxl_conf.c
+++ b/src/libxl/libxl_conf.c
@@ -796,7 +796,7 @@ libxlMakeDisk(virDomainDiskDefPtr l_disk, libxl_device_disk *x_disk)
return -1;
}
x_disk->format = LIBXL_DISK_FORMAT_RAW;
- x_disk->backend = LIBXL_DISK_BACKEND_TAP;
+ x_disk->backend = LIBXL_DISK_BACKEND_QDISK;
} else if (STREQ(driver, "phy")) {
if (format != VIR_STORAGE_FILE_NONE &&
format != VIR_STORAGE_FILE_RAW) {
--
1.8.4.5
9:56 a.m.
New subject: [libvirt] [Xen-devel] [PATCH] libxl: prefer qdisk for <driver name='file'>
On Fri, 20 Jun 2014, Jim Fehlig wrote:
The libxl driver currently sets the disk backend to
LIBXL_DISK_BACKEND_TAP when <driver name='file'> is specified
in the <disk> config. qdisk should be prefered with this
configuration, otherwise existing configuration such as the
following, which worked with the old Xen driver, will not work
with the libxl driver
<disk type='file' device='cdrom'>
<driver name='file'/>
<source file='/path/to/some/iso'/>
<target dev='hdc' bus='ide'/>
<readonly/>
</disk>
In addition, tap performs poorly compared to qdisk.
Signed-off-by: Jim Fehlig <jfehlig(a)suse.com>
Acked-by: Stefano Stabellini <stefano.stabellini(a)eu.citrix.com>
src/libxl/libxl_conf.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/libxl/libxl_conf.c b/src/libxl/libxl_conf.c
index fdbb522..4b6b5c0 100644
--- a/src/libxl/libxl_conf.c
+++ b/src/libxl/libxl_conf.c
@@ -796,7 +796,7 @@ libxlMakeDisk(virDomainDiskDefPtr l_disk, libxl_device_disk *x_disk)
return -1;
}
x_disk->format = LIBXL_DISK_FORMAT_RAW;
- x_disk->backend = LIBXL_DISK_BACKEND_TAP;
+ x_disk->backend = LIBXL_DISK_BACKEND_QDISK;
} else if (STREQ(driver, "phy")) {
if (format != VIR_STORAGE_FILE_NONE &&
format != VIR_STORAGE_FILE_RAW) {
--
1.8.4.5
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5:06 p.m.
New subject: [libvirt] [Xen-devel] [PATCH] libxl: prefer qdisk for <driver name='file'>
Stefano Stabellini wrote:
On Fri, 20 Jun 2014, Jim Fehlig wrote:
> The libxl driver currently sets the disk backend to
> LIBXL_DISK_BACKEND_TAP when <driver name='file'> is specified
> in the <disk> config. qdisk should be prefered with this
> configuration, otherwise existing configuration such as the
> following, which worked with the old Xen driver, will not work
> with the libxl driver
>
> <disk type='file' device='cdrom'>
> <driver name='file'/>
> <source file='/path/to/some/iso'/>
> <target dev='hdc' bus='ide'/>
> <readonly/>
> </disk>
>
> In addition, tap performs poorly compared to qdisk.
>
> Signed-off-by: Jim Fehlig <jfehlig(a)suse.com>
>
Acked-by: Stefano Stabellini <stefano.stabellini(a)eu.citrix.com>
Thanks Stefano. This is a change that needed blessing from one of the
Xen tools devs IMO. I've pushed the patch.
Regards,
Jim
5:53 a.m.
New subject: [libvirt] [Xen-devel] [PATCH] libxl: prefer qdisk for <driver name='file'>
On Fri, 2014-06-20 at 15:07 -0600, Jim Fehlig wrote:
The libxl driver currently sets the disk backend to
LIBXL_DISK_BACKEND_TAP when <driver name='file'> is specified
in the <disk> config. qdisk should be prefered with this
configuration, otherwise existing configuration such as the
following, which worked with the old Xen driver, will not work
with the libxl driver
OOI why not let libxl pick the most appropriate backend for (most of)
these alternatives?
<disk type='file' device='cdrom'>
<driver name='file'/>
<source file='/path/to/some/iso'/>
<target dev='hdc' bus='ide'/>
<readonly/>
</disk>
In addition, tap performs poorly compared to qdisk.
Signed-off-by: Jim Fehlig <jfehlig(a)suse.com>
---
src/libxl/libxl_conf.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/libxl/libxl_conf.c b/src/libxl/libxl_conf.c
index fdbb522..4b6b5c0 100644
--- a/src/libxl/libxl_conf.c
+++ b/src/libxl/libxl_conf.c
@@ -796,7 +796,7 @@ libxlMakeDisk(virDomainDiskDefPtr l_disk, libxl_device_disk *x_disk)
return -1;
}
x_disk->format = LIBXL_DISK_FORMAT_RAW;
- x_disk->backend = LIBXL_DISK_BACKEND_TAP;
+ x_disk->backend = LIBXL_DISK_BACKEND_QDISK;
} else if (STREQ(driver, "phy")) {
if (format != VIR_STORAGE_FILE_NONE &&
format != VIR_STORAGE_FILE_RAW) {
5:24 p.m.
New subject: [libvirt] [Xen-devel] [PATCH] libxl: prefer qdisk for <driver name='file'>
Ian Campbell wrote:
On Fri, 2014-06-20 at 15:07 -0600, Jim Fehlig wrote:
> The libxl driver currently sets the disk backend to
> LIBXL_DISK_BACKEND_TAP when <driver name='file'> is specified
> in the <disk> config. qdisk should be prefered with this
> configuration, otherwise existing configuration such as the
> following, which worked with the old Xen driver, will not work
> with the libxl driver
>
OOI why not let libxl pick the most appropriate backend for (most of)
these alternatives?
I think the libvirt approach is to be a bit more explicit, instead of
relying on hypervisor defaults that might change over time. I'm quite
sure this is the approach danpb has always advocated.
Regards,
Jim
3:50 a.m.
New subject: [libvirt] [Xen-devel] [PATCH] libxl: prefer qdisk for <driver name='file'>
On Tue, 2014-06-24 at 16:24 -0600, Jim Fehlig wrote:
Ian Campbell wrote:
> On Fri, 2014-06-20 at 15:07 -0600, Jim Fehlig wrote:
>
>> The libxl driver currently sets the disk backend to
>> LIBXL_DISK_BACKEND_TAP when <driver name='file'> is specified
>> in the <disk> config. qdisk should be prefered with this
>> configuration, otherwise existing configuration such as the
>> following, which worked with the old Xen driver, will not work
>> with the libxl driver
>>
>
> OOI why not let libxl pick the most appropriate backend for (most of)
> these alternatives?
>
I think the libvirt approach is to be a bit more explicit, instead of
relying on hypervisor defaults that might change over time. I'm quite
sure this is the approach danpb has always advocated.
I thought that policy was more for guest visible things whereas the disk
backend is transparent to the guest.
But either way it's up to libvirt.
Thanks,
Ian.
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Stefano Stabellini