From: Borislav Petkov <bp@alien8.de>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>, X86 ML <x86@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Brian Gerst <brgerst@gmail.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Oleg Nesterov <oleg@redhat.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Andrey Ryabinin <aryabinin@virtuozzo.com>
Subject: Re: [PATCH v2 3/3] x86/mm: If INVPCID is available, use it to flush global mappings
Date: Fri, 29 Jan 2016 19:27:17 +0100 [thread overview]
Message-ID: <20160129182717.GA17459@pd.tnic> (raw)
In-Reply-To: <CALCETrWhUWjfdDS6eyB6PfrJLU8YvvrfkeeKFTo8moxq7L5t6A@mail.gmail.com>
On Fri, Jan 29, 2016 at 09:35:22AM -0800, Andy Lutomirski wrote:
> I'll fiddle with that benchmark a little bit. Maybe I can make it
> suck less. If anyone knows a good non-micro benchmark for this, let
> me know.
Yeah, I don't know of a good one. The TLB and all those intermediary
walker caches modern x86 CPUs have are really good. So it is hard to
measure any improvements there. I guess in this particular case, if one
can't measure slowdowns and the code is simple enough, then we're good
enough. In theory, we are carefully killing less TLB entries and the
related cached page walker data so that should be a good thing...
> I refuse to use dbus as my benchmark :)
Ha!
> FWIW, I benchmarked cr4 vs invpcid by adding a prctl and calling it in
> a loop.
Apparently INVPCID is faster than the two CR4 writes.
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
next prev parent reply other threads:[~2016-01-29 18:27 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-25 18:37 [PATCH v2 0/3] x86/mm: INVPCID support Andy Lutomirski
2016-01-25 18:37 ` [PATCH v2 1/3] x86/mm: Add INVPCID helpers Andy Lutomirski
2016-01-29 11:19 ` Borislav Petkov
2016-01-25 18:37 ` [PATCH v2 2/3] x86/mm: Add a noinvpcid option to turn off INVPCID Andy Lutomirski
2016-01-29 11:21 ` Borislav Petkov
2016-01-25 18:37 ` [PATCH v2 3/3] x86/mm: If INVPCID is available, use it to flush global mappings Andy Lutomirski
2016-01-29 14:26 ` Borislav Petkov
2016-01-29 17:35 ` Andy Lutomirski
2016-01-29 18:27 ` Borislav Petkov [this message]
2016-01-25 18:57 ` [PATCH v2 0/3] x86/mm: INVPCID support Ingo Molnar
2016-01-27 10:09 ` several messages Thomas Gleixner
2016-01-29 13:21 ` Borislav Petkov
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