Re: [PATCH v2 2/2] virtio-ring: Allocate indirect buffers from cache when possible
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2012-09-07 00:05:07
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On Fri, Sep 07, 2012 at 09:19:04AM +0930, Rusty Russell wrote:
"Michael S. Tsirkin" [off-list ref] writes:quoted
On Thu, Sep 06, 2012 at 05:27:23PM +0930, Rusty Russell wrote:quoted
"Michael S. Tsirkin" [off-list ref] writes:quoted
Yes without checksum net core always linearizes packets, so yes it is screwed. For -net, skb always allocates space for 17 frags + linear part so it seems sane to do same in virtio core, and allocate, for -net, up to max_frags + 1 from cache. We can adjust it: no _SG -> 2 otherwise 18.But I thought it used individual buffers these days?Yes for receive, no for transmit. That's probably why we should have the threshold per vq, not per device, BTW.Can someone actually run with my histogram patch and see what the real numbers are? I'm not convinced that the ideal 17-buffer case actually happens as much as we think. And if it's not happening with this netperf test, we're testing the wrong thing. Thanks, Rusty.
hope to play with it next week