From: Rik van Riel <riel@redhat.com>
To: Borislav Petkov <bp@alien8.de>, oleg@redhat.com
Cc: dave.hansen@linux.intel.com, sbsiddha@gmail.com,
luto@amacapital.net, tglx@linutronix.de, mingo@kernel.org,
hpa@zytor.com, fenghua.yu@intel.com, x86@kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/8] x86, fpu: unlazy_fpu: don't reset thread.fpu_counter
Date: Mon, 16 Feb 2015 12:58:37 -0500 [thread overview]
Message-ID: <54E22FCD.3030202@redhat.com> (raw)
In-Reply-To: <20150216170433.GF4458@pd.tnic>
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On 02/16/2015 12:04 PM, Borislav Petkov wrote:
> ... and so by looking at the unlazy_fpu() call sites, I think this
> makes sense.
>
> So how's that for a commit message instead:
>
> --- x86, fpu, unlazy_fpu: Don't reset thread.fpu_counter
>
> The "else" branch clears ->fpu_counter as a remnant of the lazy
> FPU usage counting:
>
> e07e23e1fd30 ("[PATCH] non lazy "sleazy" fpu implementation")
>
> However, switch_fpu_prepare() does this now so that else branch is
> superfluous.
>
> If we do use_eager_fpu(), then this has no effect. Otherwise, if
> we actually wanted to prevent fpu preload after the context switch
> we would need to reset it unconditionally, even if
> __thread_has_fpu(). ---
>
> ?
Good detective work.
Your changelog makes sense to me.
- --
All rights reversed
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next prev parent reply other threads:[~2015-02-16 17:59 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-06 20:01 [PATCH 0/8] x86,fpu: various small FPU cleanups and optimizations riel
2015-02-06 20:01 ` [PATCH 1/8] x86, fpu: unlazy_fpu: don't reset thread.fpu_counter riel
2015-02-16 17:04 ` Borislav Petkov
2015-02-16 17:58 ` Rik van Riel [this message]
2015-02-16 18:14 ` Oleg Nesterov
2015-02-16 18:16 ` Borislav Petkov
2015-02-19 11:32 ` [tip:x86/fpu] x86/fpu: Don't " tip-bot for Oleg Nesterov
2015-02-06 20:01 ` [PATCH 2/8] x86, fpu: unlazy_fpu: don't do __thread_fpu_end() if use_eager_fpu() riel
2015-02-16 20:25 ` Borislav Petkov
2015-02-17 10:47 ` Oleg Nesterov
2015-02-17 12:09 ` Borislav Petkov
2015-02-19 11:32 ` [tip:x86/fpu] x86/fpu: Don't " tip-bot for Oleg Nesterov
2015-02-06 20:02 ` [PATCH 3/8] x86, fpu: kill save_init_fpu(), change math_error() to use unlazy_fpu() riel
2015-02-16 21:09 ` Borislav Petkov
2015-02-16 21:30 ` Rik van Riel
2015-02-17 10:58 ` Oleg Nesterov
2015-02-19 11:32 ` [tip:x86/fpu] x86/fpu: Change math_error() to use unlazy_fpu(), kill (now) unused save_init_fpu() tip-bot for Oleg Nesterov
2015-02-06 20:02 ` [PATCH 4/8] x86,fpu: move lazy restore functions up a few lines riel
2015-02-19 11:33 ` [tip:x86/fpu] x86/fpu: Move " tip-bot for Rik van Riel
2015-02-06 20:02 ` [PATCH 5/8] x86,fpu: introduce task_disable_lazy_fpu_restore helper riel
2015-02-19 11:33 ` [tip:x86/fpu] x86/fpu: Introduce task_disable_lazy_fpu_restore() helper tip-bot for Rik van Riel
2015-02-06 20:02 ` [PATCH 6/8] x86,fpu: use an explicit if/else in switch_fpu_prepare riel
2015-02-17 8:44 ` Borislav Petkov
2015-02-19 11:33 ` [tip:x86/fpu] x86/fpu: Use an explicit if/ else in switch_fpu_prepare() tip-bot for Rik van Riel
2015-02-06 20:02 ` [PATCH 7/8] x86,fpu: use disable_task_lazy_fpu_restore helper riel
2015-02-17 9:00 ` Borislav Petkov
2015-02-17 11:04 ` Oleg Nesterov
2015-02-17 12:11 ` Borislav Petkov
2015-02-19 11:34 ` [tip:x86/fpu] x86/fpu: Use task_disable_lazy_fpu_restore() helper tip-bot for Rik van Riel
2015-02-06 20:02 ` [PATCH 8/8] x86,fpu: also check fpu_lazy_restore when use_eager_fpu riel
2015-02-19 11:34 ` [tip:x86/fpu] x86/fpu: Also check fpu_lazy_restore() when use_eager_fpu() tip-bot for Rik van Riel
2015-02-16 15:26 ` [PATCH 0/8] x86,fpu: various small FPU cleanups and optimizations Rik van Riel
2015-02-16 16:00 ` Borislav Petkov
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