[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel][PATCH][VT] Multithread IDE device model ( was: RE: [Xen-devel] [PATCH]Make IDE dma tranfer run in another thread inqemu)
Dong, Eddie wrote: Yup, the site I linked to has two patches: a DMA patch and a concurrent IO patch.Hi Anthony: I think you made misunderstanding to this patch. Current Qemu in Xen is already DMA enabled. If I remembered correctly, it happens since we change DM from Bochs to Qemu. Without this patch, guest IO operation that trigger DMA (like port 0xc000 write) will wait in Qemu till the DMA operation iscompleted, that is original single thread IDE device model mean. With this patch, a seperate thread will service the dmaoperation started by IO operation, and interrupt target processor when it is completed, while the main thread can rapidly return to guest (like 0xc000 write). Here's a direct link: http://people.brandeis.edu/~jcoiner/qemu_idedma/qemu_concurrent_io.patch It's using the same basic approach as your patch (another thread waits for completion of IO event). I'm pointing it out though in case there's a desire to stay closer to QEMU upstream when possible. Might enable more code sharing in the future. Regards, Anthony Liguori Thanks,eddie Anthony Liguori wrote: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. Seehttp://people.brandeis.edu/~jcoiner/qemu_idedma/qemu_dma_patch.htmlThe reported performance improvement IO is up to 20% so it's definitely worth applying... Regards, Anthony Liguori _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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