From: Alex Shi <alex.shi@intel.com>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: tglx@linutronix.de, mingo@redhat.com, arnd@arndb.de,
rostedt@goodmis.org, fweisbec@gmail.com, jeremy@goop.org,
riel@redhat.com, luto@mit.edu, avi@redhat.com,
len.brown@intel.com, dhowells@redhat.com, fenghua.yu@intel.com,
borislav.petkov@amd.com, yinghai@kernel.org, ak@linux.intel.com,
cpw@sgi.com, steiner@sgi.com, akpm@linux-foundation.org,
penberg@kernel.org, hughd@google.com, rientjes@google.com,
kosaki.motohiro@jp.fujitsu.com, n-horiguchi@ah.jp.nec.com,
tj@kernel.org, oleg@redhat.com, axboe@kernel.dk,
jmorris@namei.org, a.p.zijlstra@chello.nl,
kamezawa.hiroyu@jp.fujitsu.com, viro@zeniv.linux.org.uk,
linux-kernel@vger.kernel.org, yongjie.ren@intel.com
Subject: Re: [PATCH v5 5/7] x86/tlb: add tlb_flushall_shift for specific CPU
Date: Thu, 17 May 2012 09:46:42 +0800 [thread overview]
Message-ID: <4FB45882.3010806@intel.com> (raw)
In-Reply-To: <4FB3E9FE.5020902@zytor.com>
On 05/17/2012 01:55 AM, H. Peter Anvin wrote:
> On 05/15/2012 11:49 PM, Alex Shi wrote:
>> + if (!cpu_has_invlpg || vma->vm_flags & VM_HUGETLB
>> + || tlb_flushall_shift == (u16)TLB_FLUSH_ALL) {
>
> I asked for you to fold the cpu_has_invlpg test into tlb_flushall_shift.
> Also, (u16)TLB_FLUSH_ALL really is hit up with the ugly stick... why on
> earth is this u16? It's a bit shift, so it can't be bigger than 6 bits
> anyway... and if you want to be able to use -1 as a sentinel you might
> as well make it a signed value and use < 0 or == -1 as the test.
!cpu_has_invlpg be moved in next patch, but surely, it is better to be
removed here too.
Sure, u16 make code looks ugly. So, s8 is better and worth to add value
check on later knob patch. Since this change cause later patch
modification. I am going to re-update whole patches.
>
> Am I missing something really fundamental here?
No.
>
> -hpa
>
next prev parent reply other threads:[~2012-05-17 1:48 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-15 8:55 [PATCH v5 0/7] tlb flush optimization for x86 Alex Shi
2012-05-15 8:55 ` [PATCH v5 1/7] x86/tlb: unify TLB_FLUSH_ALL definition Alex Shi
2012-05-15 8:55 ` [PATCH v5 2/7] x86/tlb_info: get last level TLB entry number of CPU Alex Shi
2012-05-15 8:55 ` [PATCH v5 3/7] x86/flush_tlb: try flush_tlb_single one by one in flush_tlb_range Alex Shi
2012-05-15 8:55 ` [PATCH v5 4/7] x86/tlb: fall back to flush all when meet a THP large page Alex Shi
2012-05-15 8:55 ` [PATCH v5 5/7] x86/tlb: add tlb_flushall_shift for specific CPU Alex Shi
2012-05-16 6:49 ` Alex Shi
2012-05-16 17:55 ` H. Peter Anvin
2012-05-17 1:46 ` Alex Shi [this message]
2012-05-15 8:55 ` [PATCH v5 6/7] x86/tlb: optimizing flush_tlb_mm Alex Shi
2012-05-15 9:11 ` Peter Zijlstra
2012-05-15 9:15 ` Nick Piggin
2012-05-15 9:17 ` Nick Piggin
2012-05-15 12:58 ` Luming Yu
2012-05-15 13:06 ` Peter Zijlstra
2012-05-15 13:27 ` Luming Yu
2012-05-15 13:28 ` Alex Shi
2012-05-15 13:33 ` Alex Shi
2012-05-15 13:39 ` Steven Rostedt
2012-05-15 14:04 ` Borislav Petkov
2012-05-15 13:08 ` Luming Yu
2012-05-15 14:07 ` Alex Shi
2012-05-15 9:18 ` Peter Zijlstra
2012-05-15 9:52 ` Nick Piggin
2012-05-15 10:00 ` Peter Zijlstra
2012-05-15 10:06 ` Nick Piggin
2012-05-15 10:13 ` Peter Zijlstra
2012-05-15 14:04 ` Alex Shi
2012-05-15 13:24 ` Alex Shi
2012-05-15 14:36 ` Peter Zijlstra
2012-05-15 14:57 ` Peter Zijlstra
2012-05-15 15:01 ` Alex Shi
2012-05-16 6:46 ` Alex Shi
2012-05-16 6:46 ` Alex Shi
2012-05-16 8:00 ` Peter Zijlstra
2012-05-16 8:04 ` Peter Zijlstra
2012-05-16 8:53 ` Alex Shi
2012-05-16 8:58 ` Peter Zijlstra
2012-05-16 10:58 ` Alex Shi
2012-05-16 11:04 ` Peter Zijlstra
2012-05-16 12:57 ` Alex Shi
2012-05-16 13:34 ` Alex Shi
2012-05-16 13:34 ` Alex Shi
2012-05-16 21:09 ` Peter Zijlstra
2012-05-17 0:43 ` Alex Shi
2012-05-17 2:07 ` Steven Rostedt
2012-05-17 8:04 ` Alex Shi
2012-05-17 2:14 ` Paul Mundt
2012-05-16 13:44 ` Alex Shi
2012-05-15 8:55 ` [PATCH v5 7/7] x86/tlb: add tlb_flushall_shift knob into debugfs Alex Shi
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