I have that patch in my tree (also touches tools/lib/); I wasn't expecting Andrew to pick it up yet. I'll send v2 in just a minute that I assume Andrew can just replace this patch with. > -----Original Message----- > From: Yury Norov [mailto:ynorov@xxxxxxxxxxxxxxxxxx] > Sent: Friday, January 6, 2017 3:08 AM > To: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>; akpm@xxxxxxxxxxxxxxxxxxxx > Cc: linux@xxxxxxxxxxxxxxxxxx; linux-arch@xxxxxxxxxxxxxxx; mm- > commits@xxxxxxxxxxxxxxx > Subject: Re: + find_bit-micro-optimise-find_next__bit.patch added to -mm tree > > NACK. > > I acked it in assumption that Matthew will send v2 that also fixes > _find_next_bit_le() the same way. > > Yury > > On Thu, Jan 05, 2017 at 05:19:06PM -0800, akpm@xxxxxxxxxxxxxxxxxxxx wrote: > > > > The patch titled > > Subject: lib/find_bit.c: micro-optimise find_next_*_bit > > has been added to the -mm tree. Its filename is > > find_bit-micro-optimise-find_next__bit.patch > > > > This patch should soon appear at > > > https://na01.safelinks.protection.outlook.com/?url=http:%2F%2Fozlabs.org%2F > ~akpm%2Fmmots%2Fbroken-out%2Ffind_bit-micro-optimise- > find_next__bit.patch&data=02%7C01%7Cmawilcox%40microsoft.com%7C39c9 > 0703ef884b0abe9708d4360b2a5e%7C72f988bf86f141af91ab2d7cd011db47% > 7C1%7C0%7C636192868992198567&sdata=I6VAxN4FZTNKaD5U%2FeCSKM5n > CYiy02uDZI1cnAdk6vc%3D&reserved=0 > > and later at > > > https://na01.safelinks.protection.outlook.com/?url=http:%2F%2Fozlabs.org%2F > ~akpm%2Fmmotm%2Fbroken-out%2Ffind_bit-micro-optimise- > find_next__bit.patch&data=02%7C01%7Cmawilcox%40microsoft.com%7C39c9 > 0703ef884b0abe9708d4360b2a5e%7C72f988bf86f141af91ab2d7cd011db47% > 7C1%7C0%7C636192868992198567&sdata=6Hp9fq8ZU4lsVu3%2FmZXKsBz2gj > sEY0y5CZvWaijx9u8%3D&reserved=0 > > > > Before you just go and hit "reply", please: > > a) Consider who else should be cc'ed > > b) Prefer to cc a suitable mailing list as well > > c) Ideally: find the original patch on the mailing list and do a > > reply-to-all to that, adding suitable additional cc's > > > > *** Remember to use Documentation/SubmitChecklist when testing your > code *** > > > > The -mm tree is included into linux-next and is updated > > there every 3-4 working days > > > > ------------------------------------------------------ > > From: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx> > > Subject: lib/find_bit.c: micro-optimise find_next_*_bit > > > > This saves 20 bytes on my x86-64 build, mostly due to alignment > > considerations ... I think it actually saves about five bytes of > > instructions. There's really two parts to this commit. First, the first > > half of the test: (!nbits || start >= nbits) is trivially a subset of the > > second half, since nbits and start are both unsigned. Second, while > > looking at the disassembly, I noticed that GCC was predicting the branch > > taken. Since this is a failure case, it's clearly the less likely of the > > two branches, so add an unlikely() to override GCC's heuristics. > > > > Link: > https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Flkml.kerne > l.org%2Fr%2F1482513603-9630-1-git-send-email- > mawilcox%40linuxonhyperv.com&data=02%7C01%7Cmawilcox%40microsoft.c > om%7C39c90703ef884b0abe9708d4360b2a5e%7C72f988bf86f141af91ab2d7c > d011db47%7C1%7C0%7C636192868992198567&sdata=69Koc35BWkngs3CPH > BsetOUPTzYsi2pHfMcgEluT2%2Fs%3D&reserved=0 > > Signed-off-by: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx> > > Acked-by: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx> > > Acked-by: Yury Norov <ynorov@xxxxxxxxxxxxxxxxxx> > > Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > > --- > > > > lib/find_bit.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff -puN lib/find_bit.c~find_bit-micro-optimise-find_next__bit lib/find_bit.c > > --- a/lib/find_bit.c~find_bit-micro-optimise-find_next__bit > > +++ a/lib/find_bit.c > > @@ -33,7 +33,7 @@ static unsigned long _find_next_bit(cons > > { > > unsigned long tmp; > > > > - if (!nbits || start >= nbits) > > + if (unlikely(start >= nbits)) > > return nbits; > > > > tmp = addr[start / BITS_PER_LONG] ^ invert; > > _ > > > > Patches currently in -mm which might be from mawilcox@xxxxxxxxxxxxx are > > > > find_bit-micro-optimise-find_next__bit.patch > > reimplement-idr-and-ida-using-the-radix-tree-support-storing-null-in-the- > idr.patch ��.n��������+%������w��{.n�����{�����ܨ}���Ơz�j:+v�����w����ޙ��&�)ߡ�a����z�ޗ���ݢj��w�f
