Re: [PATCH V5 4/4] virtio-blk: Add REQ_FLUSH and REQ_FUA support to bio path

2012-08-06 Thread Christoph Hellwig
On Thu, Aug 02, 2012 at 02:43:04PM +0800, Asias He wrote: Even if it has a payload waiting is highly suboptimal and it should use a non-blocking sequencing like it is done in the request layer. So, for REQ_FLUSH, what we need is that send out the VIRTIO_BLK_T_FLUSH and not to wait. If it's

[PATCH V5 4/4] virtio-blk: Add REQ_FLUSH and REQ_FUA support to bio path

2012-08-02 Thread Asias He
We need to support both REQ_FLUSH and REQ_FUA for bio based path since it does not get the sequencing of REQ_FUA into REQ_FLUSH that request based drivers can request. REQ_FLUSH is emulated by: 1. Send VIRTIO_BLK_T_FLUSH to device 2. Wait until the flush is finished REQ_FUA is emulated by: 1.

Re: [PATCH V5 4/4] virtio-blk: Add REQ_FLUSH and REQ_FUA support to bio path

2012-08-02 Thread Christoph Hellwig
On Thu, Aug 02, 2012 at 02:25:56PM +0800, Asias He wrote: We need to support both REQ_FLUSH and REQ_FUA for bio based path since it does not get the sequencing of REQ_FUA into REQ_FLUSH that request based drivers can request. REQ_FLUSH is emulated by: 1. Send VIRTIO_BLK_T_FLUSH to device

Re: [PATCH V5 4/4] virtio-blk: Add REQ_FLUSH and REQ_FUA support to bio path

2012-08-02 Thread Asias He
On 08/02/2012 02:27 PM, Christoph Hellwig wrote: On Thu, Aug 02, 2012 at 02:25:56PM +0800, Asias He wrote: We need to support both REQ_FLUSH and REQ_FUA for bio based path since it does not get the sequencing of REQ_FUA into REQ_FLUSH that request based drivers can request. REQ_FLUSH is