From: Stephane Eranian <eranian@frankl.hpl.hp.com>
To: linux-ia64@vger.kernel.org
Subject: Re: [Linux-ia64] What's taking all the system time..?
Date: Wed, 30 Jan 2002 06:54:10 +0000 [thread overview]
Message-ID: <marc-linux-ia64-105590698805955@msgid-missing> (raw)
In-Reply-To: <marc-linux-ia64-105590698805950@msgid-missing>
On Wed, Jan 30, 2002 at 05:46:45PM +1100, duraid@fl.net.au wrote:
> No flops in this code!
>
Sometimes, the compiler uses floating point register for integer
operations for speed reason.
> > Another potential cause could be unaligned accesses. That you can also see
> > in the system log.
>
> 'dmesg' works and sure enough, I get unaligned accesses. But not enough to get
> *that* sort of a performance hit, surely? To explain what I'm seeing, each
> unaligned access would have to cost 0.05 seconds or so!
The kernel DOES NOT generate a printk() for every unaligned accesses you
get, it's throttled. Get the address from the syslog and check the code.
You may be casting ints into pointers. Linux/ia64 uses the LP64 data
model: long and pointers are 64 bits but int are 32 bits only.
--
-Stephane
next prev parent reply other threads:[~2002-01-30 6:54 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-01-30 5:48 [Linux-ia64] What's taking all the system time..? Duraid Madina
2002-01-30 6:21 ` Stephane Eranian
2002-01-30 6:26 ` Niels Christiansen
2002-01-30 6:44 ` duraid
2002-01-30 6:46 ` duraid
2002-01-30 6:54 ` Stephane Eranian [this message]
2002-01-30 6:58 ` Niels Christiansen
2002-01-30 7:02 ` Niels Christiansen
2002-01-30 7:27 ` Niels Christiansen
2002-01-30 9:36 ` duraid
2002-01-30 10:04 ` [Linux-ia64] What's taking all the system time..? The unaligned accesses are! Duraid Madina
2002-01-30 17:43 ` [Linux-ia64] What's taking all the system time..? Boehm, Hans
2002-01-30 17:49 ` Grant Grundler
2002-01-30 18:04 ` Niels Christiansen
2002-01-30 21:57 ` Jim Wilson
2002-02-01 21:28 ` David Mosberger
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