linux-kernel - [PATCH 0/1] Try 2: Make the TSC safe to be use by gettimeofday().

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Message-ID: <455A512F.6030907@FreeBSD.org>
Date:	Tue, 14 Nov 2006 15:28:47 -0800
From:	Suleiman Souhlal <ssouhlal@...eBSD.org>
To:	Andi Kleen <ak@...e.de>
CC:	Linux Kernel ML <linux-kernel@...r.kernel.org>, vojtech@...e.cz,
	Jiri Bohac <jbohac@...e.cz>
Subject: [PATCH 0/1] Try 2: Make the TSC safe to be use by gettimeofday().

Hi,

Here are the fixes from the previous version:
- Don't use hard_smp_processor_id().
- Use the PDA to store a pointer to the current CPU's vxtime data.
- Use vgetcpu() to get the CPU number from vgettimeofday()
  (Due to a bug in vgetcpu(), this only works with CONFIG_HOTPLUG_CPU=y)
- No externs in .c files
- Use idle notifiers instead of doing the HPET read in switch_to
- Fix race in vgettimeofday() by checking the RIP of the process we're switching away from
  in switch_to, and touching the vxtime seqlock if it happens to be in the VSYSCALL page.
  (I hope this is not considered too much work for switch_to)
- Remove usage of preempt_disable/enable() in do_gettimeoday(), since the above fix make it
  unnecessary.

-- Suleiman

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