Re: [PATCH] bitmap_equal memcmp optimization for s390

2016-06-09 Thread Martin Schwidefsky
On Thu, 09 Jun 2016 15:26:47 +0100 David Howells wrote: > Martin Schwidefsky wrote: > > > I hesitate to put another CONFIG_S390 into common code, alternatively > > __HAVE_ARCH_MEMCMP could be used. There are 7 architectures with the > > define: arc, arm64, blackfin, frv, powerpc, s390 and sparc

Re: [PATCH] bitmap_equal memcmp optimization for s390

2016-06-09 Thread David Howells
Martin Schwidefsky wrote: > I hesitate to put another CONFIG_S390 into common code, alternatively > __HAVE_ARCH_MEMCMP could be used. There are 7 architectures with the > define: arc, arm64, blackfin, frv, powerpc, s390 and sparc. > Of those I guess only powerpc, s390 and sparc will have configs

[PATCH] bitmap_equal memcmp optimization for s390

2016-06-07 Thread Martin Schwidefsky
Servus, while working on an improved TLB flush logic for s390 I noticed that for s390 cpumask_equal() alias bitmap_equal() can be improved for the special case "(nbits % BITS_PER_LONG) == 0". The memcmp function can be used in this case and we have an instruction for that .. Trouble is that the d