When looking at a performance problem on PowerPC, I noticed some awful code generation: c00000000051fc98: 3b 60 00 01 li r27,1 ... c00000000051fca0: 3b 80 00 00 li r28,0 ... c00000000051fcdc: 93 61 00 70 stw r27,112(r1) c00000000051fce0: 93 81 00 74 stw r28,116(r1) c00000000051fce4: 81 21 00 70 lwz r9,112(r1) c00000000051fce8: 80 01 00 74 lwz r0,116(r1) c00000000051fcec: 7d 29 07 b4 extsw r9,r9 c00000000051fcf0: 7c 00 07 b4 extsw r0,r0 c00000000051fcf4: 7c 20 04 ac lwsync c00000000051fcf8: 7d 60 f8 28 lwarx r11,0,r31 c00000000051fcfc: 7c 0b 48 00 cmpw r11,r9 c00000000051fd00: 40 c2 00 10 bne- c00000000051fd10 c00000000051fd04: 7c 00 f9 2d stwcx. r0,0,r31 c00000000051fd08: 40 c2 ff f0 bne+ c00000000051fcf8 c00000000051fd0c: 4c 00 01 2c isync We create two constants, write them out to the stack, read them straight back in and sign extend them. What a mess. It turns out this bad code is a result of us defining atomic_t as a volatile int. We removed the volatile attribute from the powerpc atomic_t definition years ago, but commit ea435467500612636f8f4fb639ff6e76b2496e4b (atomic_t: unify all arch definitions) added it back in. To dig up an old quote from Linus: > The fact is, volatile on data structures is a bug. It's a wart in the C > language. It shouldn't be used. > > Volatile accesses in *code* can be ok, and if we have "atomic_read()" > expand to a "*(volatile int *)&(x)->value", then I'd be ok with that. > > But marking data structures volatile just makes the compiler screw up > totally, and makes code for initialization sequences etc much worse. And screw up it does :) With the volatile removed, we see much more reasonable code generation: c00000000051f5b8: 3b 60 00 01 li r27,1 ... c00000000051f5c0: 3b 80 00 00 li r28,0 ... c00000000051fc7c: 7c 20 04 ac lwsync c00000000051fc80: 7c 00 f8 28 lwarx r0,0,r31 c00000000051fc84: 7c 00 d8 00 cmpw r0,r27 c00000000051fc88: 40 c2 00 10 bne- c00000000051fc98 c00000000051fc8c: 7f 80 f9 2d stwcx. r28,0,r31 c00000000051fc90: 40 c2 ff f0 bne+ c00000000051fc80 c00000000051fc94: 4c 00 01 2c isync Six instructions less. Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Follow-up to "block: enable by default support for large devices and files on 32-bit archs". Rename CONFIG_LBD to CONFIG_LBDAF to: - allow update of existing [def]configs for "default y" change - reflect that it is used also for large files support nowadays Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
With the last used of non-strict names gone from the exported header files, we can remove the old libc5 compatibility cruft from our headers and only export strict types. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Reported-by: Sam Ravnborg <sam@ravnborg.org> Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
The typedefs for __u64 and __s64 where fixed to be available for other compiler on May 2 2008 by H. Peter Anvin (in commit edfa5cfa3dc5) Acked-by: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Detlef Riekenberg <wine.dev@web.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The atomic_t type cannot currently be used in some header files because it would create an include loop with asm/atomic.h. Move the type definition to linux/types.h to break the loop. Signed-off-by: Matthew Wilcox <willy@linux.intel.com> Cc: Huang Ying <ying.huang@intel.com> Cc: <linux-arch@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We have two seperate config entries for large devices/files. One is CONFIG_LBD that guards just the devices, the other is CONFIG_LSF that handles large files. This doesn't make a lot of sense, you typically want both or none. So get rid of CONFIG_LSF and change CONFIG_LBD wording to indicate that it covers both. Acked-by: Jean Delvare <khali@linux-fr.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
There's no good reason why a resource_size_t shouldn't just be a physical address, so simply redefine it in terms of phys_addr_t. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>