linux-kernel - Re: [PATCH v4 3/7] x86/flush_tlb: try flush_tlb_single one by one in flush_tlb

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Date:	Thu, 10 May 2012 16:42:31 -0500
From:	Rob Landley <rob@...dley.net>
To:	Alex Shi <alex.shi@...el.com>
CC:	Borislav Petkov <bp@...64.org>, tglx@...utronix.de,
	mingo@...hat.com, hpa@...or.com, arnd@...db.de,
	rostedt@...dmis.org, fweisbec@...il.com, jeremy@...p.org,
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	fenghua.yu@...el.com, ak@...ux.intel.com, cpw@....com,
	steiner@....com, akpm@...ux-foundation.org, penberg@...nel.org,
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	kosaki.motohiro@...fujitsu.com, n-horiguchi@...jp.nec.com,
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	kamezawa.hiroyu@...fujitsu.com, viro@...iv.linux.org.uk,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 3/7] x86/flush_tlb: try flush_tlb_single one by one
 in flush_tlb_range

On 05/10/2012 03:50 AM, Alex Shi wrote:
>>
> 
>> Ok, question:
>>
>> we're comparing TLB size with the amount of pages mapped by this mm
>> struct. AFAICT, that doesn't mean that all those mapped pages do have
>> respective entries in the TLB, does it?
>>
>> If so, then the actual entries number is kinda inaccurate, no? We don't
>> really know how many TLB entries actually belong to this mm struct. Or am I
>> missing something?
> 
> No, we can not know the exactly TLB entires for. But usually, when you
> process is doing the mprotect/munmap etc system call, your process has
> taken much of memory and already filled lots of TLB entries.

$ strace true 2>&1 | grep mprotect
mprotect(0x7f67a934b000, 2093056, PROT_NONE) = 0
mprotect(0x7f67a954a000, 16384, PROT_READ) = 0
mprotect(0x607000, 4096, PROT_READ)     = 0
mprotect(0x7f67a9773000, 4096, PROT_READ) = 0

This appears to be part of glibc process setup. Define "usually".

Rob
-- 
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Either it's "mere aggregation", or a license violation.  Pick one.
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