From: Christoph Lameter <cl@linux.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Subject: Why do we still have 32 bit counters? Interrupt counters overflow within 50 days
Date: Fri, 3 Oct 2014 04:45:08 -0500 (CDT) [thread overview]
Message-ID: <alpine.DEB.2.11.1410030435260.8324@gentwo.org> (raw)
struct irq_desc still has
unsigned int irq_count;
A timer interrupt occurs 1000 times per second and there are 86400 seconds
in a day. There is a counter for the local timer interrupt that needs to
be continually incremented.
So the counter will overflow in
2^32 / 1000 / 86400 = 46 days
Diagnostic tools will be surprised by the counters suddenly going back to
zero. There may be other interrupt sources that also occur quite often.
Is this the way its intended or should the counters be expanded to 64 bit?
64 bit would last for our lifetime.
next reply other threads:[~2014-10-03 9:45 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-03 9:45 Christoph Lameter [this message]
2014-10-03 10:33 ` Why do we still have 32 bit counters? Interrupt counters overflow within 50 days Thomas Gleixner
2014-10-03 11:54 ` Christoph Lameter
2014-10-03 12:03 ` Richard Cochran
2014-10-03 12:07 ` Christoph Lameter
2014-10-03 12:17 ` Richard Cochran
2014-10-03 14:04 ` Christoph Lameter
2014-10-05 21:49 ` Thomas Gleixner
2014-10-05 23:24 ` Christoph Lameter
2014-10-05 23:57 ` Eric Dumazet
2014-10-06 8:06 ` Thomas Gleixner
2014-10-06 10:22 ` Christoph Lameter
2014-10-06 13:01 ` Thomas Gleixner
2014-10-06 15:16 ` Christoph Lameter
2014-10-06 15:28 ` Thomas Gleixner
2014-10-06 19:34 ` Henrique de Moraes Holschuh
2014-10-06 15:31 ` David Lang
2014-10-06 19:45 ` Christoph Lameter
2014-10-05 23:59 ` Eric Dumazet
2014-10-06 7:54 ` Thomas Gleixner
2014-10-06 10:49 ` David Lang
2014-10-06 12:28 ` Thomas Gleixner
2014-10-03 12:15 ` Paul Bolle
2014-10-03 12:23 ` Christoph Lameter
2014-10-04 10:26 ` Bernd Petrovitsch
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