Messages in this thread | | | Subject | Re: [PATCH] Fix a huge latency problem in the MTD CFI and LPDDR flash drivers. | From | Stefani Seibold <> | Date | Fri, 23 Apr 2010 08:03:04 +0200 |
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Hi Andrew,
David did not respond to my request since more than a month. Can u apply the patch to linux next?
Thanks, Stefani
Am Dienstag, den 20.04.2010, 20:16 +0200 schrieb Stefani Seibold: > Is the MTD mailing list routed to /dev/null? > > It is very sad that nobody gives my a reply. > > I ask for a merge for the patch, and if there any reason why not, it > would be great to know. Otherwise i can't fix it. > > So again, please merge the path for the huge latency problem. > > Am Sonntag, den 18.04.2010, 22:46 +0200 schrieb Stefani Seibold: > > From: Stefani Seibold <stefani@seibold.net> > > > > The use of a memcpy() during a spinlock operation will cause very long > > thread context switch delays if the flash chip bandwidth is low and the > > data to be copied large, because a spinlock will disable preemption. > > > > For example: A flash with 6,5 MB/s bandwidth will cause under ubifs, > > which request sometimes 128 KB (the flash erase size), a preemption delay of > > 20 milliseconds. High priority threads will not be served during this > > time, regardless whether this threads access the flash or not. This behavior > > breaks real time. > > > > The patch changes all the use of spin_lock operations for xxxx->mutex > > into mutex operations, which is exact what the name says and means. > > > > I have checked the code of the drivers and there is no use of atomic > > pathes like interrupt or timers. The mtdoops facility will also not be used > > by this drivers. So it is dave to replace the spin_lock against mutex. > > > > There is no performance regression since the mutex is normally not > > acquired. > > > > Changelog: > > 06.03.2010 First release > > 26.03.2010 Fix mutex[1] issue and tested it for compile failure > > > > Signed-off-by: Stefani Seibold <stefani@seibold.net> > > --- > > drivers/mtd/chips/cfi_cmdset_0001.c | 131 +++++++++++++++++----------------- > > drivers/mtd/chips/cfi_cmdset_0002.c | 122 ++++++++++++++++---------------- > > drivers/mtd/chips/cfi_cmdset_0020.c | 136 +++++++++++++++++----------------- > > drivers/mtd/chips/fwh_lock.h | 6 +- > > drivers/mtd/chips/gen_probe.c | 3 +- > > drivers/mtd/lpddr/lpddr_cmds.c | 79 ++++++++++---------- > > include/linux/mtd/flashchip.h | 4 +- > > 7 files changed, 239 insertions(+), 242 deletions(-) >
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