From: "H. Peter Anvin" <hpa@zytor.com>
To: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Ingo Molnar <mingo@kernel.org>, Len Brown <lenb@kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [patch] x86, tlb: switch cr3 in leave_mm() only when needed
Date: Thu, 22 Mar 2012 17:20:20 -0700 [thread overview]
Message-ID: <4F6BC1C4.6050502@zytor.com> (raw)
In-Reply-To: <1332460885.16101.147.camel@sbsiddha-desk.sc.intel.com>
On 03/22/2012 05:01 PM, Suresh Siddha wrote:
>
> Agreed. Updated patch appended. Thanks.
> ---
> From: Suresh Siddha <suresh.b.siddha@intel.com>
> Subject: x86, tlb: switch cr3 in leave_mm() only when needed
>
> Currently leave_mm() unconditionally switches the cr3 to swapper_pg_dir.
> But there is no need to change the cr3, if we already left that mm.
>
> intel_idle() for example calls leave_mm() on every deep c-state entry where
> the CPU flushes the TLB for us. Similarly flush_tlb_all() was also calling
> leave_mm() whenever the TLB is in LAZY state. Both these paths will be
> improved with this change.
>
> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
>
Looks great to me. Linus, do you want this one later in the window if
it tests out OK between now and then, or is it too late?
-hpa
--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.
next prev parent reply other threads:[~2012-03-23 0:20 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-22 23:33 [patch] x86, tlb: switch cr3 in leave_mm() only when needed Suresh Siddha
2012-03-22 23:44 ` Linus Torvalds
2012-03-23 0:01 ` Suresh Siddha
2012-03-23 0:20 ` H. Peter Anvin [this message]
2012-03-23 0:37 ` Linus Torvalds
2012-03-23 0:51 ` Suresh Siddha
2012-03-23 8:37 ` Ingo Molnar
2012-03-26 22:47 ` Suresh Siddha
2012-03-26 22:47 ` H. Peter Anvin
2012-03-23 0:31 ` [tip:x86/mm] x86, tlb: Switch " tip-bot for Suresh Siddha
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