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Message-ID: <cover.1305846412.git.mst@redhat.com> Date: Fri, 20 May 2011 02:10:07 +0300 From: "Michael S. Tsirkin" <mst@...hat.com> To: linux-kernel@...r.kernel.org Cc: Rusty Russell <rusty@...tcorp.com.au>, Carsten Otte <cotte@...ibm.com>, Christian Borntraeger <borntraeger@...ibm.com>, linux390@...ibm.com, Martin Schwidefsky <schwidefsky@...ibm.com>, Heiko Carstens <heiko.carstens@...ibm.com>, Shirley Ma <xma@...ibm.com>, lguest@...ts.ozlabs.org, linux-kernel@...r.kernel.org, virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org, linux-s390@...r.kernel.org, kvm@...r.kernel.org, Krishna Kumar <krkumar2@...ibm.com>, Tom Lendacky <tahm@...ux.vnet.ibm.com>, steved@...ibm.com, habanero@...ux.vnet.ibm.com Subject: [PATCHv2 00/14] virtio and vhost-net performance enhancements OK, here is the large patchset that implements the virtio spec update that I sent earlier (the spec itself needs a minor update, will send that out too next week, but I think we are on the same page here already). It supercedes the PUBLISH_USED_IDX patches I sent out earlier. What will follow will be a patchset that actually includes 4 sets of patches. I note below their status. Please consider for 2.6.40, at least partially. Rusty, do you think it's feasible? List of patches and what they do: I) With the first patchset, we change virtio ring notification hand-off to work like the one in Xen - each side publishes an event index, the other one notifies when it reaches that value - With the one difference that event index starts at 0, same as request index (in xen event index starts at 1). These are the patches in this set: virtio: event index interface virtio ring: inline function to check for events virtio_ring: support event idx feature vhost: support event index virtio_test: support event index Changes in this part of the patchset from v1 - address comments by Rusty et al. I tested this a lot with virtio net block and with the simulator and esp with the simulator it's easy to see drastic performance improvement here: [virtio]# time ./virtio_test spurious wakeus: 0x7 real 0m0.169s user 0m0.140s sys 0m0.019s [virtio]# time ./virtio_test --no-event-idx spurious wakeus: 0x11 real 0m0.649s user 0m0.295s sys 0m0.335s And these patches are mostly unchanged from the very first version, changes being almost exclusively code cleanups. So I consider this part the most stable, I strongly think these patches should go into 2.6.40. One extra reason besides performance is that maintaining them out of tree is very painful as guest/host ABI is affected. II) Second set of patches: new apis and use in virtio_net With the indexes in place it becomes possibile to request an event after many requests (and not just on the next one as done now). This shall fix the TX queue overrun which currently triggers a storm of interrupts. Another issue I tried to fix is capacity checks in virtio-net, there's a new API for that, and on top of that, I implemented a patch improving real-time characteristics of virtio_net Thus we get the second patchset: virtio: add api for delayed callbacks virtio_net: delay TX callbacks virtio_ring: Add capacity check API virtio_net: fix TX capacity checks using new API virtio_net: limit xmit polling This has some fixes that I posted previously applied, but otherwise ideantical to v1. I tried to change API for enable_cb_delayed as Rusty suggested but failed to do this. I think it's not possible to define cleanly. These work fine for me, I think they can be merged for 2.6.40 too but would be nice to hear back from Shirley, Tom, Krishna. III) There's also a patch that adds a tweak to virtio ring virtio: don't delay avail index update This seems to help small message sizes where we are constantly draining the RX VQ. I'll need to benchmark this to be able to give any numbers with confidence, but I don't see how it can hurt anything. Thoughts? IV) Last part is a set of patches to extend feature bits to 64 bit. I tested this by using feature bit 32. vhost: fix 64 bit features virtio_test: update for 64 bit features virtio: 64 bit features It's nice to have as set I used up the last free bit. But not a must now that a single bit controls use of event index on both sides. The patchset is on top of net-next which at the time I last rebased was 15ecd03 - so roughly 2.6.39-rc2. For testing I usually do merge v2.6.39 on top. qemu patch is also ready. Code can be pulled from here: git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git vhost-net-next-event-idx-v3 git://git.kernel.org/pub/scm/linux/kernel/git/mst/qemu-kvm.git virtio-net-event-idx-v3 Rusty, I think it will be easier to merge vhost and virtio bits in one go. Can it all go in through your tree (Dave in the past acked sending a very similar patch through you so should not be a problem)? -- 1.7.5.53.gc233e Michael S. Tsirkin (13): virtio: event index interface virtio ring: inline function to check for events virtio_ring: support event idx feature vhost: support event index virtio_test: support event index virtio: add api for delayed callbacks virtio_net: delay TX callbacks virtio_net: fix TX capacity checks using new API virtio_net: limit xmit polling virtio: don't delay avail index update virtio: 64 bit features virtio_test: update for 64 bit features vhost: fix 64 bit features Shirley Ma (1): virtio_ring: Add capacity check API drivers/lguest/lguest_device.c | 8 +- drivers/net/virtio_net.c | 27 +++++--- drivers/s390/kvm/kvm_virtio.c | 8 +- drivers/vhost/net.c | 12 ++-- drivers/vhost/test.c | 6 +- drivers/vhost/vhost.c | 138 ++++++++++++++++++++++++++++++---------- drivers/vhost/vhost.h | 29 +++++--- drivers/virtio/virtio.c | 8 +- drivers/virtio/virtio_pci.c | 34 ++++++++-- drivers/virtio/virtio_ring.c | 87 ++++++++++++++++++++++--- include/linux/virtio.h | 16 ++++- include/linux/virtio_config.h | 15 +++-- include/linux/virtio_pci.h | 9 ++- include/linux/virtio_ring.h | 29 ++++++++- tools/virtio/virtio_test.c | 27 +++++++- 15 files changed, 348 insertions(+), 105 deletions(-) -- 1.7.5.53.gc233e -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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