Re: [libvirt] [PATCHv2 2/2] Add txmode attribute to interface XML for virtio backend
On 02/09/2011 10:14 AM, Laine Stump wrote:
The resulting difference, according to the qemu developer who added
the option is:
bh makes tx more asynchronous and reduces latency, but potentially
causes more processor bandwidth contention since the cpu doing the
tx isn't necessarily the cpu where the guest generated the
packets.
This sentence (or something derived from it, using our names of
iothread|timer) should be in docs/formatdomain.html.in.
Changes from v1:
1) add error log / abort domain startup if option isn't supported by qemu
2) change attribute name from tx_alg to txmode
3) change attribute values from bh|timer to iothread|timer
All seem reasonable.
(The difference in length between full patch and delta diff was small
enough that I decided to just resend the full patch.)
src/conf/domain_conf.c | 26 +++++++++++++++++++++++++-
src/conf/domain_conf.h | 11 +++++++++++
src/qemu/qemu_capabilities.c | 3 +++
src/qemu/qemu_capabilities.h | 1 +
src/qemu/qemu_command.c | 27 +++++++++++++++++++++++++++
5 files changed, 67 insertions(+), 1 deletions(-)
Incomplete - need a v3 (or at least a follow-up patch) that touches
docs/schemas/domain.rng, adds at least one test of the new attribute in
tests/qemuxml2argvdata/, and documents the issue.
@@ -1367,6 +1377,7 @@ VIR_ENUM_DECL(virDomainFS)
VIR_ENUM_DECL(virDomainFSAccessMode)
VIR_ENUM_DECL(virDomainNet)
VIR_ENUM_DECL(virDomainNetBackend)
+VIR_ENUM_DECL(virDomainNetVirtioTxMode)
Also missing two new entries in src/libvirt_private.syms.
@@ -1104,6 +1105,8 @@ qemuCapsParseDeviceStr(const char *str,
unsigned long long *flags)
if (strstr(str, "pci-assign.bootindex"))
*flags |= QEMUD_CMD_FLAG_PCI_BOOTINDEX;
}
+ if (strstr(str, "virtio-net-pci.tx="))
+ *flags |= QEMUD_CMD_FLAG_VIRTIO_TX_ALG;
It's a race between your patch and Jirka's bitmap cleanup :)
Is this something that needs to go in 0.8.8, or should we wait until
post-release?
Looks better, but I don't feel comfortable giving this ack without a
completion of the patch series.
--
Eric Blake eblake(a)redhat.com +1-801-349-2682
Libvirt virtualization library http://libvirt.org
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