From: Dave Hansen <dave.hansen@linux.intel.com>
To: Nadav Amit <nadav.amit@gmail.com>, Andy Lutomirski <luto@amacapital.net>
Cc: x86@kernel.org, Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
linux-kernel@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
Andy Lutomirski <luto@kernel.org>
Subject: Re: [PATCH] x86: Align TLB invalidation info
Date: Wed, 31 Jan 2018 12:49:47 -0800 [thread overview]
Message-ID: <1e0c2666-d0ee-8fe2-3272-6b49bf045834@linux.intel.com> (raw)
In-Reply-To: <747E60F0-2315-4BEC-895E-0E29C57A0AF0@gmail.com>
On 01/31/2018 12:48 PM, Nadav Amit wrote:
>>> On Jan 31, 2018, at 12:11 PM, Nadav Amit <namit@vmware.com> wrote:
>>>
>>> The TLB invalidation info is allocated on the stack, which might cause
>>> it to be unaligned. Since this information may be transferred to
>>> different cores for TLB shootdown, this might result in an additional
>>> cache-line bouncing between the cores.
>>>
>>> GCC provides a way to deal with it by using
>>> __builtin_alloca_with_align(). Use it to avoid the bouncing cache lines.
>> Eww. How about __aligned?
> Err.. Stupid me. For some reason I remembered I tried it and it didn’t have
> the desired effect, which caused me to assume it does not work for variables
> on the stack. Anyhow, it does the work. I’ll submit v2.
Also, just curious, but did you find this situation by inspection or did
it show up in a profile somewhere?
next prev parent reply other threads:[~2018-01-31 20:49 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-31 20:11 [PATCH] x86: Align TLB invalidation info Nadav Amit
2018-01-31 20:24 ` Andy Lutomirski
2018-01-31 20:48 ` Nadav Amit
2018-01-31 20:49 ` Dave Hansen [this message]
2018-01-31 20:52 ` Nadav Amit
2018-01-31 21:00 ` Andy Lutomirski
2018-01-31 21:01 ` Dave Hansen
2018-01-31 21:09 ` Nadav Amit
2018-01-31 21:15 ` Andy Lutomirski
2018-01-31 21:17 ` Nadav Amit
[not found] ` <f7270e0d-d1d1-599d-d2c9-ddc2c263e090@linux.intel.com>
2018-02-01 5:38 ` Nadav Amit
2018-02-01 9:38 ` Peter Zijlstra
2018-02-01 18:45 ` Nadav Amit
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