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From: Ingo Molnar <mingo@kernel.org>
To: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: irq_fpu_usable() is irreliable
Date: Wed, 18 Nov 2015 07:55:08 +0100	[thread overview]
Message-ID: <20151118065508.GA18849@gmail.com> (raw)
In-Reply-To: <CAHmME9pTPzCzZSVaO5vKT+0gaZwu424v4AzBMfM1opAdwkMbYg@mail.gmail.com>


* Jason A. Donenfeld <Jason@zx2c4.com> wrote:

> [...] Recently I've been tracking down a problem in which irq_fpu_usable() 
> returns false, yet a stack trace shows the first function is the syscall entry 
> point. [...]

Is this 'problem' a performance problem (code not being able to use the FPU 
occasionally and hence sporadically performing poorly), or some sort of actual 
stability/correctness problem?

Also, what CPU does the test system have, Intel or AMD? The FPU behavior can be 
very different in the two cases.

Third, could you post such a problematic stack trace?

Thanks,

	Ingo

  reply	other threads:[~2015-11-18  6:55 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-17 11:39 irq_fpu_usable() is irreliable Jason A. Donenfeld
2015-11-18  6:55 ` Ingo Molnar [this message]
2015-11-18 12:16   ` Jason A. Donenfeld
2015-11-18 19:59     ` Jason A. Donenfeld
2015-11-27  8:41       ` Ingo Molnar
2015-11-27  8:47     ` Ingo Molnar
     [not found] <CAHmME9rgXh3zQDfc2Yo_Au0CSg--X+ak=SQdS9DoXNsKK0TPmA@mail.gmail.com>
2015-11-17 14:06 ` Thomas Gleixner
2015-11-17 14:51   ` Jason A. Donenfeld
2015-11-17 19:54     ` Jason A. Donenfeld

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