Messages in this thread | | | Date | Thu, 03 Dec 2009 07:05:55 -0800 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH RFC] [X86] Compile Option Os versus O2 on latest x86 platform |
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On 12/03/2009 07:03 AM, Ma, Ling wrote: >> a key question is.. how much more memory do you have free due to -Os? >> (because memory is cache is performance on a system level as well) > The kernel code size from Os is 12M, that from O2 is 14M. >> and how much less icache pressure is there? > From perf stat report, cache reference(unified cache) from O2 is almost the same with Os.
The icache pressure was substantially higher (by ~10%) in the reports that I saw.
-hpa
-- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.
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