lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Mon, 30 Jul 2012 11:25:51 +0930 From: Rusty Russell <rusty@...tcorp.com.au> To: "Michael S. Tsirkin" <mst@...hat.com>, Asias He <asias@...hat.com> Cc: linux-kernel@...r.kernel.org, virtualization@...ts.linux-foundation.org, kvm@...r.kernel.org, Christoph Hellwig <hch@....de>, Minchan Kim <minchan.kim@...il.com> Subject: Re: [PATCH V4 3/3] virtio-blk: Add bio-based IO path for virtio-blk On Sun, 29 Jul 2012 14:11:15 +0300, "Michael S. Tsirkin" <mst@...hat.com> wrote: > On Sat, Jul 28, 2012 at 10:21:05AM +0800, Asias He wrote: > > This patch introduces bio-based IO path for virtio-blk. > > > > Compared to request-based IO path, bio-based IO path uses driver > > provided ->make_request_fn() method to bypasses the IO scheduler. It > > handles the bio to device directly without allocating a request in block > > layer. This reduces the IO path in guest kernel to achieve high IOPS > > and lower latency. The downside is that guest can not use the IO > > scheduler to merge and sort requests. However, this is not a big problem > > if the backend disk in host side uses faster disk device. > > If this optimization depends on the host, then it > should be reported to the guest using a feature bit, > as opposed to being guest driven. I consider this approach a half-way step. Quick attempts on my laptop and I couldn't find a case where the bio path was a loss, but in theory if the host wasn't doing any reordering and it was a slow device, you'd want the guest to do so. I'm not sure if current qemu can be configured to do such a thing? Cheers, Rusty. -- 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/
Powered by blists - more mailing lists