RE: [PATCH v1 1/1] mmc: block: replace __blk_end_request() with blk_end_request()

["Subhash Jadavani" <subhashj@codeaurora.org>]

Hi Chris,

Do you see any issues with this patch?

Regards,
Subhash

> -----Original Message-----
> From: Subhash Jadavani [mailto:subhashj@codeaurora.org]
> Sent: Wednesday, April 18, 2012 1:07 PM
> To: 'Namjae Jeon'
> Cc: 'Chris Ball'; 'linux-mmc@vger.kernel.org'; 'linux-arm-
> msm@vger.kernel.org'
> Subject: RE: [PATCH v1 1/1] mmc: block: replace __blk_end_request() with
> blk_end_request()
> 
> Hi Namjae,
> 
> > -----Original Message-----
> > From: Namjae Jeon [mailto:linkinjeon@gmail.com]
> > Sent: Wednesday, April 18, 2012 11:12 AM
> > To: Subhash Jadavani
> > Cc: Chris Ball; linux-mmc@vger.kernel.org;
> > linux-arm-msm@vger.kernel.org
> > Subject: Re: [PATCH v1 1/1] mmc: block: replace __blk_end_request()
> > with
> > blk_end_request()
> >
> > Hi. Subhash.
> >
> > Would you share which option you used in LMDD, iozone test ?
> 
> Following are the commands. Page cache is flushed before next iteration.
> Original numbers shared were average of almost 10 iterations.
> 
> LMDD:
> 	100MB file read/write:
> 		write:
> 			lmdd if=internal of=/data/datafile bs=128k count=800
> flush=1 sync=1
> 		read:
> 			lmdd if=/data/datafile of=internal bs=128k flush=1
> sync=1
> 
> IOZONE:
> 	100MB file read/write:
> 		Write:
> 			iozone -i0 -s100m -r128k -e -w -f /data/datafile -U
> /data/
> 		Read:
> 			iozone -i1 -s100m -r128k -e -f /data/datafile -U /data/
> 
> Regards,
> Subhash
> 
> >
> > Thanks.
> >
> > 2012/4/18 Subhash Jadavani <subhashj@codeaurora.org>:
> > > Hi Chris,
> > >
> > >> -----Original Message-----
> > >> From: linux-arm-msm-owner@vger.kernel.org [mailto:linux-arm-msm-
> > >> owner@vger.kernel.org] On Behalf Of Subhash Jadavani
> > >> Sent: Wednesday, April 11, 2012 12:22 AM
> > >> To: 'Chris Ball'
> > >> Cc: linux-mmc@vger.kernel.org; linux-arm-msm@vger.kernel.org
> > >> Subject: RE: [PATCH v1 1/1] mmc: block: replace __blk_end_request()
> > >> with
> > >> blk_end_request()
> > >>
> > >>
> > >>
> > >> > -----Original Message-----
> > >> > From: Chris Ball [mailto:cjb@laptop.org]
> > >> > Sent: Wednesday, April 11, 2012 12:08 AM
> > >> > To: Subhash Jadavani
> > >> > Cc: linux-mmc@vger.kernel.org; linux-arm-msm@vger.kernel.org
> > >> > 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   <cjb@laptop.org>   <http://printf.net/> One Laptop
> > >> > Per Child
> > >>
> > >> --
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