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

["Subhash Jadavani" <subhashj@xxxxxxxxxxxxxx>]

Hi Namjae,

> -----Original Message-----
> From: Namjae Jeon [mailto:linkinjeon@xxxxxxxxx]
> Sent: Wednesday, April 18, 2012 11:12 AM
> To: Subhash Jadavani
> Cc: Chris Ball; linux-mmc@xxxxxxxxxxxxxxx; linux-arm-msm@xxxxxxxxxxxxxxx
> 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@xxxxxxxxxxxxxx>:
> > Hi Chris,
> >
> >> -----Original Message-----
> >> From: linux-arm-msm-owner@xxxxxxxxxxxxxxx [mailto:linux-arm-msm-
> >> owner@xxxxxxxxxxxxxxx] On Behalf Of Subhash Jadavani
> >> Sent: Wednesday, April 11, 2012 12:22 AM
> >> To: 'Chris Ball'
> >> Cc: linux-mmc@xxxxxxxxxxxxxxx; linux-arm-msm@xxxxxxxxxxxxxxx
> >> Subject: RE: [PATCH v1 1/1] mmc: block: replace __blk_end_request()
> >> with
> >> blk_end_request()
> >>
> >>
> >>
> >> > -----Original Message-----
> >> > From: Chris Ball [mailto:cjb@xxxxxxxxxx]
> >> > Sent: Wednesday, April 11, 2012 12:08 AM
> >> > To: Subhash Jadavani
> >> > Cc: linux-mmc@xxxxxxxxxxxxxxx; linux-arm-msm@xxxxxxxxxxxxxxx
> >> > 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@xxxxxxxxxx>   <http://printf.net/> One Laptop Per
> >> > Child
> >>
> >> --
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