Re: getting processor numbers

From: Eric Dumazet
Date: Wed Apr 04 2007 - 01:47:15 EST


H. Peter Anvin a Ãcrit :
Jeremy Fitzhardinge wrote:
H. Peter Anvin wrote:
Mutable data should be separated from code. I think any current CPU
will do fine as long as they are in separate 128-byte chunks, but they
need at least that much separation.
P4 manual says that if one processor modifies data within 2k of another
processor executing code, it will trash the entire trace cache.

Yuck. Didn't realize the P4 was that sensitive. OK, so at the least we need a half-page of separation.

Yes but vsyscall API currently defines 4 entry points :

vsyscall0 (vgettimeofday) = ADDR
vsyscall1 (vtime) = ADDR+1024
vsyscall2 (vgetcpu) = ADDR+2048
vsyscall3 (vxxxxx) = ADDR+3072

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