Hi Chris, > -----Original Message----- > From: [email protected] [mailto:linux-arm-msm- > [email protected]] On Behalf Of Subhash Jadavani > Sent: Wednesday, April 11, 2012 12:22 AM > To: 'Chris Ball' > Cc: [email protected]; [email protected] > Subject: RE: [PATCH v1 1/1] mmc: block: replace __blk_end_request() with > blk_end_request() > > > > > -----Original Message----- > > From: Chris Ball [mailto:[email protected]] > > Sent: Wednesday, April 11, 2012 12:08 AM > > To: Subhash Jadavani > > Cc: [email protected]; [email protected] > > Subject: Re: [PATCH v1 1/1] mmc: block: replace __blk_end_request() > > with > > blk_end_request() > > > > Hi, > > > > On Tue, Apr 10 2012, Subhash Jadavani wrote: > > > This patch replaces all __blk_end_request() calls with > > > blk_end_request() and __blk_end_request_all() calls with > > > blk_end_request_all(). > > > > > > Testing done: 20 process concurrent read/write on sd card and eMMC. > > > Ran this test for almost a day on multicore system and no errors > > > observed. > > > > Is there a measurable improvement in throughput or latency that you > > can > show > > data for? > > This change was not meant for improving MMC throughput; it's basically about > becoming fair to other threads/interrupts in the system. By holding spin lock > and interrupts disabled for longer duration, we won't allow other > threads/interrupts to run at all. > Actually slight performance degradation at file system level can be expected as > we are not holding the spin lock during blk_update_bidi_request() which means > our mmcqd thread may get preempted for other high priority thread or any > interrupt in the system. > > > These are performance numbers (100MB file write) with eMMC running in > DDR > mode: > > Without this patch: > Name of the Test Value Unit > LMDD Read Test 53.79 MBPS > LMDD Write Test 18.86 MBPS > IOZONE Read Test 51.65 MBPS > IOZONE Write Test 24.36 MBPS > > With this patch: > > Name of the Test Value Unit > LMDD Read Test 52.94 MBPS > LMDD Write Test 16.70 MBPS > IOZONE Read Test 52.08 MBPS > IOZONE Write Test 23.29 MBPS > > Read numbers are fine. Write numbers are bit down (especially LMDD write), > may be because write requests normally have large transfer size and which > means there are chances that while mmcq is executing > blk_update_bidi_request(), it may get interrupted by interrupts or other high > priority thread.
Any thoughts/suggestions on this patch and numbers? Regards, Subhash > > Regards, > Subhash > > > > > Thanks, > > > > - Chris. > > -- > > Chris Ball <[email protected]> <http://printf.net/> > > One Laptop Per Child > > -- > To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the > body of a message to [email protected] More majordomo info at > http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
