On 04/28/2015 02:59 AM, Mike Snitzer wrote: > From: Christoph Hellwig <hch@xxxxxx> > > Currently dm-multipath has to clone the bios for every request sent > to the lower devices, which wastes cpu cycles and ties down memory. > > This patch instead adds a new REQ_CLONE flag that instructs req_bio_endio > to not complete bios attached to a request, which we set on clone > requests similar to bios in a flush sequence. With this change I/O > errors on a path failure only get propagated to dm-multipath, which > can then either resubmit the I/O or complete the bios on the original > request. > > I've done some basic testing of this on a Linux target with ALUA support, > and it survives path failures during I/O nicely. > > Signed-off-by: Christoph Hellwig <hch@xxxxxx> > Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx> Reviewed-by: Hannes Reinecke <hare@xxxxxxx> Cheers, Hannes -- Dr. Hannes Reinecke zSeries & Storage hare@xxxxxxx +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG Nürnberg) -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
