xen-devel
Re: [Xen-devel][PATCH][VT] Multithread IDE device model ( was: RE: [Xen-
Dong, Eddie wrote:
Keir:
This is to to make the IDE device model multithreading so that
the VMX domain IO access completion (triggering DMA operation) can be
asynchronize with the completion of DMA operation. With this patch we
get 8%--14% performance gain for kernel build.
Thanks,
eddie
Hi Eddie,
There was a patch floating around on qemu-devel recently to make IDE DMA
concurrent. Fabrice is planning to include it in QEMU as long as there
are no regressions. It may already be in CVS.
See http://people.brandeis.edu/~jcoiner/qemu_idedma/qemu_dma_patch.html
The reported performance improvement IO is up to 20% so it's definitely
worth applying...
Regards,
Anthony Liguori
Yang, Xiaowei wrote:
Originally in qemu when a IDE dma transfer is started which is
triggered by access to 0xc000 port in VMX, qemu will blocked there
until it finished. And during that block, there are extra dom
switches between dom0 and idle domain, and VMX can't be resumed. By
making real IDE dma tranfer run in another thread, qemu will return
and VMX resume on time and there are fewer cycle wasted.
Signed-off-by: Ke Yu <ke.yu@xxxxxxxxx>
Signed-off-by: Xiaowei Yang <xiaowei.yang@xxxxxxxxx>
-Xiaowei
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