On Thu, 11 Oct 2012 17:19:01 +0200, Per Forlin <per.lkml@xxxxxxxxx> wrote: Hello Per, >I would like to start with some basic comments. > >1. Is this read sequential issue specific to MMC? >2. Or is it common with all other block-drivers that gets data from >the block layer (SCSI/SATA etc) ? >If (#2) can the issue be addressed inside the block layer instead? > >BR >Per This issue specific to MMC, others block drivers probably not using MMC mechanism for async request (or have more kernel threads for processing incoming blk requests). I think, since MMC actively fetches requests from block layer queue, the solution has nothing to do with block layer context. > >On Tue, Oct 2, 2012 at 5:39 PM, Konstantin Dorfman ><kdorfman@xxxxxxxxxxxxxx> wrote: >> The main assumption of the async request design is that the file >> system adds block requests to the block device queue asynchronously >> without waiting for completion (see the Rationale section of >> https://wiki.linaro.org/WorkingGroups/Kernel/Specs >> /StoragePerfMMC-async-req). >> >> We found out that in case of sequential read operations this is not >> the case, due to the read ahead mechanism. >Would it be possible to improve this mechanism to achieve the same result? >Allow an outstanding read ahead request on top of the current ongoing one. > I need to look on this mechanism, but from first glance such behaviour may be result of libc/vfs/fs decisions and too complex comparing to the patch we are talking about. -- Konstantin Dorfman, QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
