Re: [PATCH v2 2/2] virtio-ring: Allocate indirect buffers from cachewhen possible

From: Paolo Bonzini
Date: Mon Sep 10 2012 - 11:52:45 EST


Il 06/09/2012 07:02, Michael S. Tsirkin ha scritto:
>> > It might be worth just unconditionally having a cache for the 2
>> > descriptor case. This is what I get with qemu tap, though for some
>> > reason the device features don't have guest or host CSUM, so my setup is
>> > probably screwed:
> 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.
>
> Not sure about other drivers, maybe really use 2 there for now.

2 should also be good for virtio-blk and virtio-scsi 4KB random rw
workloads.

Paolo

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/