On Thu, Jul 27, 2017 at 10:25:25AM +0530, Anup Patel wrote: > On Wed, Jul 26, 2017 at 10:40 PM, Vinod Koul <vinod.koul@xxxxxxxxx> wrote: > > On Wed, Jul 26, 2017 at 11:06:40AM +0530, Anup Patel wrote: > >> We should peek mbox channels when we are left with no free > >> sba_requests in sba_alloc_request() > > > > and why is the world should we do that, how does that help?? > > When setting up RAID array on several NVMe disk we observed > that sba_alloc_request() start failing (due to no free requests left) > and RAID array setup becomes very slow. > > Doing mbox channel peek when we have no free requests left, > improves performance of RAID array setup. How about documenting this tribal knowledge in the changelog. Changelogs are very useful, 6 months down the line, you will struggle to remember why this was changed.. > > This change is inspired from mv_chan_alloc_slot() implemented > in drivers/dma/mv_xor.c > > Regards, > Anup -- ~Vinod -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
