Messages in this thread | | | Date | Wed, 4 Jan 2006 19:17:47 -0500 | From | Chuck Ebbert <> | Subject | Re: [patch 2.6.15] i386: Optimize local APIC timer interrupt code |
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In-Reply-To: <20060104150139.34829833.akpm@osdl.org>
Andrew Morton wrote:
> The code which you're patching is cheerfully nuked by a patch in Andi's > tree: > ftp://ftp.firstfloor.org/pub/ak/x86_64/quilt-current/patches/no-subjiffy-profile > > I don't immediately understand that patch and I don't recall seeing it > discussed - maybe I was asleep. > > It removes the profile multiplier (readprofile -M). I've used that > occasionally, but can't say that I noticed much benefit from it.
It's probably required for the i386-timer-broadcast patch from the same patchset. Apparently some Intel CPUs stop their local APIC timer when in certain ACPI C-states, so that patch switches them to use an IPI broadcast from the main timer interrupt instead. Supporting subjiffy profiling is impossible in that case, so the code was removed.
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