From: Sheng Yang <sheng@linux.intel.com>
To: Beth Kon <eak@us.ibm.com>
Cc: kvm@vger.kernel.org
Subject: The HPET issue on Linux
Date: Wed, 6 Jan 2010 17:48:52 +0800 [thread overview]
Message-ID: <201001061748.52689.sheng@linux.intel.com> (raw)
Hi Beth
I still found the emulated HPET would result in some boot failure. For
example, on my 2.6.30, with HPET enabled, the kernel would fail check_timer(),
especially in timer_irq_works().
The testing of timer_irq_works() is let 10 ticks pass(using mdelay()), and
want to confirm the clock source with at least 5 ticks advanced in jiffies.
I've checked that, on my machine, it would mostly get only 4 ticks when HPET
enabled, then fail the test. On the other hand, if I using PIT, it would get
more than 10 ticks(maybe understandable if some complementary ticks there). Of
course, extend the ticks count/mdelay() time can work.
I think it's a major issue of HPET. And it maybe just due to a too long
userspace path for interrupt injection... If it's true, I think it's not easy
to deal with it.
--
regards
Yang, Sheng
next reply other threads:[~2010-01-06 9:50 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-06 9:48 Sheng Yang [this message]
2010-01-06 10:09 ` The HPET issue on Linux Gleb Natapov
2010-01-06 10:23 ` Dor Laor
2010-01-06 18:36 ` Beth Kon
2010-01-06 19:20 ` Beth Kon
2010-01-06 19:23 ` Anthony Liguori
2010-01-06 19:44 ` Gleb Natapov
2010-01-06 19:51 ` Anthony Liguori
2010-01-06 20:37 ` Gleb Natapov
2010-01-06 22:42 ` Anthony Liguori
2010-01-07 6:45 ` Gleb Natapov
2010-01-07 3:01 ` Sheng Yang
2010-02-02 18:13 ` No longer working on HPET Beth Kon
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