On Fri, 10 Aug 2018, Joe Perches wrote: > On Fri, 2018-08-10 at 16:02 -0400, Nicolas Pitre wrote: > > On Fri, 10 Aug 2018, Joe Perches wrote: > > > > > On Fri, 2018-08-10 at 14:12 -0500, Jeff Lien wrote: > > > > This patch provides a performance improvement for the CRC16 calculations done in read/write > > > > workloads using the T10 Type 1/2/3 guard field. For example, today with sequential write > > > > workloads (one thread/CPU of IO) we consume 100% of the CPU because of the CRC16 computation > > > > bottleneck. Today's block devices are considerably faster, but the CRC16 calculation prevents > > > > folks from utilizing the throughput of such devices. To speed up this calculation and expose > > > > the block device throughput, we slice the old single byte for loop into a 16 byte for loop, > > > > with a larger CRC table to match. The result has shown 5x performance improvements on various > > > > big endian and little endian systems running the 4.18.0 kernel version. > > > > > > Thanks. > > > > > > This seems a sensible tradeoff for the 4k text size increase. > > > > More like 7.5KB. Would be best if this was configurable so the small > > version remained available. > > Maybe something like: (compiled, untested) > --- > crypto/Kconfig | 10 + > crypto/crct10dif_common.c | 543 +++++++++++++++++++++++++++++++++++++++++++++- > 2 files changed, 549 insertions(+), 4 deletions(-) > > diff --git a/crypto/Kconfig b/crypto/Kconfig > index f3e40ac56d93..88d9d17bb18a 100644 > --- a/crypto/Kconfig > +++ b/crypto/Kconfig > @@ -618,6 +618,16 @@ config CRYPTO_CRCT10DIF > a crypto transform. This allows for faster crc t10 diff > transforms to be used if they are available. > > +config CRYPTO_CRCT10DIF_TABLE_SIZE > + int "Size of CRCT10DIF crc tables (as a power of 2)" > + depends on CRYPTO_CRCT10DIF > + range 1 5 > + default 1 if EMBEDDED > + default 5 You could even make the prompt depend on EXPERT. I like it! Acked-by: Nicolas Pitre <nico@xxxxxxxxxx> Nicolas
