Anton Blanchard <an...@samba.org> writes: > Hi Aneesh, > >> yes. We do use jump label. I also verified that looking at .s >> >> #APP >> # 23 "./arch/powerpc/include/asm/jump_label.h" 1 >> 1: >> nop >> .pushsection __jump_table, "aw" >> .llong 1b, .L201, __tracepoint_hash_fault+8 #, >> .popsection >> >> # 0 "" 2 > > So we insert a single nop, and the slow path is in another section. I'd > be surprised if we could measure this, unless the nop causes a branch > target alignment issue the slow path caused some hot path icache layout > issues. > >> Without patch >> sys: 0m11.2425 >> >> With patch: >> sys: 0m11.3258 >> >> ie, a -0.7% impact >> >> If that impact is high we could possibly put that tracepoint within >> #ifdef CONFIG_DEBUG_VM ? > > Did the real time change? I'd be careful about comparing based on > system time.
Yes it did. 11.8769 with patch 11.7924 without patch I will look at the perf stat data difference between the both runs and update. -aneesh _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
