Re: [Qemu-devel] Question about posixaio thread number.
On Wed, Aug 3, 2011 at 6:19 AM, Gui Jianfeng wrote: > When i did some io tests in Guest say dd like > dd if=/dev/zero oflag=direct of=/mnt/sdb1/date.img bs=4k count=262114 > > qemu will start one or several threads to perform IO requests. > > It seems qemu makes use of its own posixaio. I'm wondering how qemu > decides how many threads should be created to perform io operation? Look at posix-aio-compat.c. If a new request comes in and there is no idle thread around, a new thread will be spawned up to a maximum limit. When you run a synchronous I/O workload like dd(1), expect to see only 1 or 2 aio worker threads. If the workload is multithreaded, expect to see many (depending on the guest's queue depth). Stefan
[Qemu-devel] Question about posixaio thread number.
Hi Anthony, I started a guest with cache=none and aio=threads When i did some io tests in Guest say dd like dd if=/dev/zero oflag=direct of=/mnt/sdb1/date.img bs=4k count=262114 qemu will start one or several threads to perform IO requests. It seems qemu makes use of its own posixaio. I'm wondering how qemu decides how many threads should be created to perform io operation? Thanks, Gui
[Qemu-devel] Question about posixaio thread number.
Hi Anthony, I started a guest with cache=none and aio=threads When i did some io tests in Guest say dd like dd if=/dev/zero oflag=direct of=/mnt/sdb1/date.img bs=4k count=262114 qemu will start one or several threads to perform IO requests. It seems qemu makes use of its own posixaio. I'm wondering how qemu decides how many threads should be created to perform io operation? Thanks, Gui
