From: Dave Hansen <dave.hansen@linux.intel.com>
To: Nadav Amit <namit@vmware.com>, x86@kernel.org
Cc: 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>,
Nadav Amit <nadav.amit@gmail.com>,
Andy Lutomirski <luto@kernel.org>
Subject: Re: [PATCH] x86: Align TLB invalidation info
Date: Wed, 31 Jan 2018 13:01:24 -0800 [thread overview]
Message-ID: <8bb352bc-4e1f-4e87-80e3-a8e65d618d2a@linux.intel.com> (raw)
In-Reply-To: <20180131201118.1694-1-namit@vmware.com>
On 01/31/2018 12:11 PM, Nadav Amit 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.
It doesn't really *bounce*, though, does it? I don't see any writes on
the remote side. The remote use seems entirely read-only.
You also don't have to exhaustively test this, but I'd love to see at
least a sanity check with a microbenchmark (or something) that, yes,
this does help *something*. Maybe it makes the remote
flush_tlb_func_common() run faster because it's pulling in fewer lines,
or maybe you can even detect fewer misses in there.
next prev parent reply other threads:[~2018-01-31 21:01 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
2018-01-31 20:52 ` Nadav Amit
2018-01-31 21:00 ` Andy Lutomirski
2018-01-31 21:01 ` Dave Hansen [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=8bb352bc-4e1f-4e87-80e3-a8e65d618d2a@linux.intel.com \
--to=dave.hansen@linux.intel.com \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@kernel.org \
--cc=mingo@redhat.com \
--cc=nadav.amit@gmail.com \
--cc=namit@vmware.com \
--cc=peterz@infradead.org \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.