[PATCH] tsc-disable_B7

From: john stultz (johnstul@us.ibm.com)
Date: Mon Aug 05 2002 - 17:58:07 EST

        This patch enables a workaround for multi-node NUMA systems that are
experiencing gettimeofday returning "old" time values. Because these
systems are frequently driven by different crystals, the CPUs vary
slightly in frequency causing the TSCs to drift apart. Thus it is
possible for gettimeofday to return time values behind time values
already seen on another cpu. This patch allows people compiling w/
'Multi-node NUMA support' to pass "notsc" or "bad-tsc" as boot
parameters. "notsc" disables rdtsc calls, and forces the kernel to use
the PIT for gettimeofday calucluations (as normally expected w/ i386
compiled kernels). While "bad-tsc" forces the kernel to use the PIT for
gettimeofday, but does not disable TSC access.

Thanks to Matt Wilson for suggestions on this revision.

Comments, suggestions and flames welcome.


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

This archive was generated by hypermail 2b29 : Wed Aug 07 2002 - 22:00:29 EST