On Fri, Sep 13 2013 at 3:22pm -0400, Mike Snitzer <snitzer@xxxxxxxxxx> wrote: > On Fri, Sep 13 2013 at 2:59pm -0400, > Mike Snitzer <snitzer@xxxxxxxxxx> wrote: > > > You can pull these changes from the 'devel' branch of: > > git://git.kernel.org/pub/scm/linux/kernel/git/snitzer/linux.git > > > > To browse, see: > > https://git.kernel.org/cgit/linux/kernel/git/snitzer/linux.git/log/?h=devel > > > > v2 changes: > > Simplified the implementation. Dropped the peak_reserved_rq_based_ios > > tracking, we'll use the tracepoint patch Jun'ichi Nomura suggested: > > http://www.redhat.com/archives/dm-devel/2013-September/msg00048.html > > This needs a v3 because the simplified code doesn't handle bounds > properly (previous version handled remapping 0 to defaults). But we > also need a maximum value that we're willing to support. So if the user > exceeds that value it is reset to the max supported. Here is an incremental diff: diff --git a/drivers/md/dm.c b/drivers/md/dm.c index a617fe3..033dc26 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -213,6 +213,7 @@ struct dm_md_mempools { #define RESERVED_BIO_BASED_IOS 16 #define RESERVED_REQUEST_BASED_IOS 256 +#define RESERVED_MAX_IOS 1024 static struct kmem_cache *_io_cache; static struct kmem_cache *_rq_tio_cache; @@ -226,15 +227,36 @@ static unsigned reserved_bio_based_ios = RESERVED_BIO_BASED_IOS; */ static unsigned reserved_rq_based_ios = RESERVED_REQUEST_BASED_IOS; +static unsigned __dm_get_reserved_ios(unsigned *reserved_ios, + unsigned def, unsigned max) +{ + unsigned ios = ACCESS_ONCE(*reserved_ios); + unsigned modified_ios = 0; + + if (!ios) + modified_ios = def; + else if (ios > max) + modified_ios = max; + + if (modified_ios) { + (void)cmpxchg(reserved_ios, ios, modified_ios); + ios = modified_ios; + } + + return ios; +} + unsigned dm_get_reserved_bio_based_ios(void) { - return ACCESS_ONCE(reserved_bio_based_ios); + return __dm_get_reserved_ios(&reserved_bio_based_ios, + RESERVED_BIO_BASED_IOS, RESERVED_MAX_IOS); } EXPORT_SYMBOL_GPL(dm_get_reserved_bio_based_ios); unsigned dm_get_reserved_rq_based_ios(void) { - return ACCESS_ONCE(reserved_rq_based_ios); + return __dm_get_reserved_ios(&reserved_rq_based_ios, + RESERVED_REQUEST_BASED_IOS, RESERVED_MAX_IOS); } EXPORT_SYMBOL_GPL(dm_get_reserved_rq_based_ios); -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
