From: Paolo Bonzini <pbonzini@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
Sasha Levin <levinsasha928@gmail.com>,
avi@redhat.com
Subject: Re: [PATCH v2 2/2] virtio-ring: Allocate indirect buffers from cache when possible
Date: Mon, 10 Sep 2012 17:52:41 +0200 [thread overview]
Message-ID: <504E0CC9.1040905@redhat.com> (raw)
In-Reply-To: <20120906050257.GA17656@redhat.com>
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
WARNING: multiple messages have this Message-ID (diff)
From: Paolo Bonzini <pbonzini@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>,
linux-kernel@vger.kernel.org, avi@redhat.com,
Sasha Levin <levinsasha928@gmail.com>,
kvm@vger.kernel.org, virtualization@lists.linux-foundation.org
Subject: Re: [PATCH v2 2/2] virtio-ring: Allocate indirect buffers from cache when possible
Date: Mon, 10 Sep 2012 17:52:41 +0200 [thread overview]
Message-ID: <504E0CC9.1040905@redhat.com> (raw)
In-Reply-To: <20120906050257.GA17656@redhat.com>
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
next prev parent reply other threads:[~2012-09-10 15:52 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-28 13:04 [PATCH v2 1/2] virtio-ring: Use threshold for switching to indirect descriptors Sasha Levin
2012-08-28 13:04 ` Sasha Levin
2012-08-28 13:04 ` [PATCH v2 2/2] virtio-ring: Allocate indirect buffers from cache when possible Sasha Levin
2012-08-28 13:04 ` Sasha Levin
2012-08-28 13:20 ` Michael S. Tsirkin
2012-08-28 13:20 ` Michael S. Tsirkin
2012-08-28 13:35 ` Sasha Levin
2012-08-28 13:35 ` Sasha Levin
2012-08-29 11:07 ` Michael S. Tsirkin
2012-08-29 11:07 ` Michael S. Tsirkin
2012-08-29 15:03 ` Sasha Levin
2012-08-29 15:03 ` Sasha Levin
2012-08-29 15:14 ` Michael S. Tsirkin
2012-08-29 15:14 ` Michael S. Tsirkin
2012-08-30 10:34 ` Sasha Levin
2012-08-30 10:34 ` Sasha Levin
2012-08-29 15:38 ` Michael S. Tsirkin
2012-08-29 15:38 ` Michael S. Tsirkin
2012-08-29 16:50 ` Sasha Levin
2012-08-29 16:50 ` Sasha Levin
2012-09-06 1:02 ` Rusty Russell
2012-09-06 1:02 ` Rusty Russell
2012-09-06 5:02 ` Michael S. Tsirkin
2012-09-06 5:02 ` Michael S. Tsirkin
2012-09-06 7:57 ` Rusty Russell
2012-09-06 7:57 ` Rusty Russell
2012-09-06 8:45 ` Michael S. Tsirkin
2012-09-06 8:45 ` Michael S. Tsirkin
2012-09-06 23:49 ` Rusty Russell
2012-09-06 23:49 ` Rusty Russell
2012-09-07 0:06 ` Michael S. Tsirkin
2012-09-07 0:06 ` Michael S. Tsirkin
2012-09-10 15:47 ` Thomas Lendacky
2012-09-10 16:08 ` Michael S. Tsirkin
2012-09-10 16:08 ` Michael S. Tsirkin
2012-09-12 6:13 ` Rusty Russell
2012-09-12 6:13 ` Rusty Russell
2012-09-12 10:44 ` Sasha Levin
2012-09-12 10:44 ` Sasha Levin
2012-10-23 15:14 ` Michael S. Tsirkin
2012-10-23 15:14 ` Michael S. Tsirkin
2012-09-10 16:01 ` Thomas Lendacky
2012-09-10 16:01 ` Thomas Lendacky
2012-09-10 15:52 ` Paolo Bonzini [this message]
2012-09-10 15:52 ` Paolo Bonzini
2012-09-06 0:02 ` Rusty Russell
2012-09-06 0:02 ` Rusty Russell
2012-08-29 15:38 ` Michael S. Tsirkin
2012-08-29 15:38 ` Michael S. Tsirkin
2012-08-29 17:14 ` Sasha Levin
2012-08-29 17:14 ` Sasha Levin
2012-08-29 18:12 ` Michael S. Tsirkin
2012-08-29 18:12 ` Michael S. Tsirkin
2012-08-29 20:46 ` Sasha Levin
2012-08-29 20:46 ` Sasha Levin
2012-08-29 22:52 ` Michael S. Tsirkin
2012-08-29 22:52 ` Michael S. Tsirkin
2012-08-28 13:20 ` [PATCH v2 1/2] virtio-ring: Use threshold for switching to indirect descriptors Michael S. Tsirkin
2012-08-28 13:20 ` Michael S. Tsirkin
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