Messages in this thread | | | Date | Sun, 17 Jan 2010 07:05:17 +0100 | From | Ingo Molnar <> | Subject | Re: x86: clean up rwsem type system |
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* H. Peter Anvin <hpa@zytor.com> wrote:
> On 01/12/2010 06:16 PM, Linus Torvalds wrote: > > > > In case anybody wants to test, the final piece is appended. > > > > Again, note the 32767-thread limit here. So this really does need that > > whole "make rwsem_count_t be 64-bit and fix the BIAS values to match" > > extension on top of it, but that is conceptually a totally independent > > issue. > > > > NOT TESTED! The original patch that this all was based on were tested by > > KAMEZAWA Hiroyuki, but maybe I screwed up something when I created the > > cleaned-up series, so caveat emptor.. > > > > Also note that it _may_ be a good idea to mark some more registers > > clobbered on x86-64 in the inline asms instead of saving/restoring them. > > They are inline functions, but they are only used in places where there > > are not a lot of live registers _anyway_, so doing for example the > > clobbers of %r8-%r11 in the asm wouldn't make the fast-path code any > > worse, and would make the slow-path code smaller. > > > > Hi Linus, > > I have put these into a separate topic branch in the tip tree, which should > get them some test coverage. I will look at 64-bit counters to support 2^31 > threads hopefully later this week, unless you prefer to do it yourself.
FYI, -tip testing found that these changes break the UML build:
kernel/built-in.o: In function `__up_read': /home/mingo/tip/arch/x86/include/asm/rwsem.h:192: undefined reference to `call_rwsem_wake' kernel/built-in.o: In function `__up_write': /home/mingo/tip/arch/x86/include/asm/rwsem.h:210: undefined reference to `call_rwsem_wake' kernel/built-in.o: In function `__downgrade_write': /home/mingo/tip/arch/x86/include/asm/rwsem.h:228: undefined reference to `call_rwsem_downgrade_wake' kernel/built-in.o: In function `__down_read': /home/mingo/tip/arch/x86/include/asm/rwsem.h:112: undefined reference to `call_rwsem_down_read_failed' kernel/built-in.o: In function `__down_write_nested': /home/mingo/tip/arch/x86/include/asm/rwsem.h:154: undefined reference to `call_rwsem_down_write_failed' collect2: ld returned 1 exit status
Ingo
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