Messages in this thread | | | Date | Thu, 22 Jan 2009 16:08:15 -0800 | From | Jeremy Fitzhardinge <> | Subject | Re: lmbench lat_mmap slowdown with CONFIG_PARAVIRT |
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H. Peter Anvin wrote: > Right now a number of the call sites contain a huge push/pop sequence > followed by an indirect call. We can patch in the native code to > avoid the branch overhead, but the register constraints and icache > footprint is unchanged.
That's true for the pvops hooks emitted in the .S files, but not so true for ones in C code (well, there are no explicit push/pops, but the presence of the call may cause the compiler to generate them).
The .S hooks can definitely be cleaned up, but I don't think that's germane to Nick's observations that the mm code is showing slowdowns.
J
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