On 03/19/2015 10:13 AM, Sam Bobroff wrote: > This patch changes the syscall handler to doom (tabort) active > transactions when a syscall is made and return immediately without > performing the syscall. > > Currently, the system call instruction automatically suspends an > active transaction which causes side effects to persist when an active > transaction fails. > > This does change the kernel's behaviour, but in a way that was > documented as unsupported. It doesn't reduce functionality because > syscalls will still be performed after tsuspend. It also provides a > consistent interface and makes the behaviour of user code > substantially the same across powerpc and platforms that do not > support suspended transactions (e.g. x86 and s390). > > Performance measurements using > http://ozlabs.org/~anton/junkcode/null_syscall.c > indicate the cost of a system call increases by about 0.5%.
Performance test results verified which shows an improvement of around ~0.52% with the patch compared to without it. [With patch] null_syscall: 757.59 cycles 100.00% [Without patch]] null_syscall: 753.66 cycles 100.00% > > Signed-off-by: Sam Bobroff <sam.bobr...@au1.ibm.com> Tested-by: Anshuman Khandual <khand...@linux.vnet.ibm.com> _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
