Messages in this thread | | | Subject | Re: Performance analysis of Linux Kernel Markers 0.20 for 2.6.17 | From | Nicholas Miell <> | Date | Sat, 30 Sep 2006 21:19:42 -0700 |
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On Sat, 2006-09-30 at 23:42 -0400, Mathieu Desnoyers wrote: > * Nicholas Miell (nmiell@comcast.net) wrote: > > > > Has anyone done any performance measurements with the "regular function > > call replaced by a NOP" type of marker? > > > > Here it is (on the same setup as the other tests : Pentium 4, 3 GHz) : > > * Execute an empty loop > > - Without marker > NR_LOOPS : 10000000 > time delta (cycles): 15026497 > cycles per loop : 1.50 > > - With 5 NOPs > NR_LOOPS : 100000 > time delta (cycles): 300157 > cycles per loop : 3.00 > added cycles per loop for nops : 3.00-1.50 = 1.50 > > > * Execute a loop of memcpy 4096 bytes > > - Without marker > NR_LOOPS : 10000 > time delta (cycles): 12981555 > cycles per loop : 1298.16 > > - With 5 NOPs > NR_LOOPS : 10000 > time delta (cycles): 12983925 > cycles per loop : 1298.39 > added cycles per loop for nops : 0.23 > > > If we compare this approach to the jump-over-call markers (in cycles per loop) : > > NOPs Jump over call generic Jump over call optimized > empty loop 1.50 1.17 2.50 > memcpy 0.23 2.12 0.07 > > > > Mathieu
What about with two NOPs (".byte 0x66, 0x66, 0x90, 0x66, 0x90" - this should work with everything) or one (".byte 0x0f, 0x1f, 0x44, 0x00, 0x00" - AFAIK, this should work with P6 or newer).
(Sorry, I should have mentioned this the first time.)
-- Nicholas Miell <nmiell@comcast.net>
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