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Subject: Re: [PATCH 00/11] Use global pages with PTI
To:     Ingo Molnar <mingo@kernel.org>
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Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-mm <linux-mm@kvack.org>,
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From:   Dave Hansen <dave.hansen@linux.intel.com>
Message-ID: <3cdc23a2-99eb-6f93-6934-f7757fa30a3e@linux.intel.com>
Date:   Fri, 30 Mar 2018 13:26:14 -0700
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On 03/30/2018 05:17 AM, Ingo Molnar wrote:
> BTW., the expectation on !PCID Intel hardware would be for global pages to help 
> even more than the 0.6% and 1.7% you measured on PCID hardware: PCID already 
> _reduces_ the cost of TLB flushes - so if there's not even PCID then global pages 
> should help even more.
> 
> In theory at least. Would still be nice to measure it.

I did the lseek test on a modern, non-PCID system:

No Global pages (baseline): 6077741 lseeks/sec
94 Global pages (this set): 8433111 lseeks/sec
			   +2355370 lseeks/sec (+38.8%)