Messages in this thread Patch in this message | | | Date | Tue, 23 Oct 2012 17:14:43 +0200 | From | "Michael S. Tsirkin" <> | Subject | Re: [PATCH v2 2/2] virtio-ring: Allocate indirect buffers from cache when possible |
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On Wed, Sep 12, 2012 at 12:44:47PM +0200, Sasha Levin wrote: > On 09/12/2012 08:13 AM, Rusty Russell wrote: > > The real question is now whether we'd want a separate indirect cache for > > the 3 case (so num above should be a bitmap?), or reuse the same one, or > > not use it at all? > > > > Benchmarking will tell... > > Since there are no specific decisions about actual values, I'll just modify the > code to use cache per-vq instead of per-device. > > > Thanks, > Sasha
One wonders whether we can still use the slab caches and improve the locality by aligning the size. Something like the below - this passed basic testing but didn't measure performance yet.
virtio: align size for indirect buffers
Improve locality for indirect buffer allocations and avoid false cache sharing by aligning allocations to cache line size.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 2fc85f2..93e6c3a 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -119,7 +119,8 @@ static int vring_add_indirect(struct vring_virtqueue *vq, unsigned head; int i; - desc = kmalloc((out + in) * sizeof(struct vring_desc), GFP_ATOMIC); + desc = kmalloc(L1_CACHE_ALIGN((out + in) * sizeof(struct vring_desc)), + GFP_ATOMIC); if (!desc) return vq->vring.num;
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