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Date: Tue, 26 Aug 2014 16:38:31 +0800
From: "Zhang Haoyu" <zhanghy@sangfor.com>
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Subject: Re: [Qemu-devel] [PATCH v6 0/3] linux-aio: introduce submit I/O
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To: Fam Zheng <famz@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Peter Maydell <peter.maydell@linaro.org>, "Michael S. Tsirkin" <mst@redhat.com>, Stefan Hajnoczi <stefanha@gmail.com>, Ming Lei <ming.lei@canonical.com>, qemu-devel <qemu-devel@nongnu.org>, Stefan Hajnoczi <stefanha@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>

>> Can we use the queued io data as caches, 
>> io write will directly return and tell the guest the io is completed after the io is enqueued, 
>> better user experience for burst io,
>> and io-read will firstly search the io queue, if matched data found, directly get the data from the queue, 
>> if not, then read the data from the disk or host page cache.
>> Any ideas?
>
>Guest kernel already has a page cache that exactly does this, also keeping a
>copy of guest request data in qemu may hurt the bandwidth in some cases.
>
You are right.
Does the io merging in queue is worthy to be performed ?

Thanks,
Zhang Haoyu
>Fam