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From: Christopher Covington <cov-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
To: Pawel Moll <pawel.moll-5wv7dgnIgG8@public.gmane.org>
Cc: Richard Cochran
	<richardcochran-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	Steven Rostedt <rostedt-nx8X9YLhiw1AfugRpC6u6w@public.gmane.org>,
	Ingo Molnar <mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>,
	Paul Mackerras <paulus-eUNUBHrolfbYtjvyW6yDsg@public.gmane.org>,
	Arnaldo Carvalho de Melo
	<acme-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	John Stultz <john.stultz-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>,
	"linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
	<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	"linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
	<linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: [RFC 2/2] perf: Marker software event and ioctl
Date: Fri, 12 Sep 2014 10:00:09 -0400	[thread overview]
Message-ID: <5412FC69.8080709@codeaurora.org> (raw)
In-Reply-To: <1410526672.16936.52.camel@hornet>

On 09/12/2014 08:57 AM, Pawel Moll wrote:
> On Fri, 2014-09-12 at 13:43 +0100, Christopher Covington wrote:
>> Just to ask the dumb questions in case the answers I've come up with are
>> wrong: What is PAGE_SIZE on an arm64 kernel? 
> 
> It's either 4 or 64k, depending on CONFIG_ARM64_64K_PAGES.
> 
>> How does userspace know?
>>
> #include <unistd.h>
> #include <stdio.h>
> 
> int main(void)
> {
> 	printf("%ld\n", sysconf(_SC_PAGESIZE));
> 	return 0;
> }

Oh excellent, that actually works. Based on a misreading of the glibc code I
thought it was hard-coded to 64K.

Thanks,
Christopher

-- 
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by the Linux Foundation.

WARNING: multiple messages have this Message-ID (diff)
From: Christopher Covington <cov@codeaurora.org>
To: Pawel Moll <pawel.moll@arm.com>
Cc: Richard Cochran <richardcochran@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Paul Mackerras <paulus@samba.org>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	John Stultz <john.stultz@linaro.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-api@vger.kernel.org" <linux-api@vger.kernel.org>
Subject: Re: [RFC 2/2] perf: Marker software event and ioctl
Date: Fri, 12 Sep 2014 10:00:09 -0400	[thread overview]
Message-ID: <5412FC69.8080709@codeaurora.org> (raw)
In-Reply-To: <1410526672.16936.52.camel@hornet>

On 09/12/2014 08:57 AM, Pawel Moll wrote:
> On Fri, 2014-09-12 at 13:43 +0100, Christopher Covington wrote:
>> Just to ask the dumb questions in case the answers I've come up with are
>> wrong: What is PAGE_SIZE on an arm64 kernel? 
> 
> It's either 4 or 64k, depending on CONFIG_ARM64_64K_PAGES.
> 
>> How does userspace know?
>>
> #include <unistd.h>
> #include <stdio.h>
> 
> int main(void)
> {
> 	printf("%ld\n", sysconf(_SC_PAGESIZE));
> 	return 0;
> }

Oh excellent, that actually works. Based on a misreading of the glibc code I
thought it was hard-coded to 64K.

Thanks,
Christopher

-- 
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by the Linux Foundation.

  parent reply	other threads:[~2014-09-12 14:00 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-12 11:48 [RFC 0/2] Yet another take at user/kernel time correlation problem Pawel Moll
2014-09-12 11:48 ` [RFC 1/2] perf: Add sampling of the raw monotonic clock Pawel Moll
     [not found] ` <1410522513-1045-1-git-send-email-pawel.moll-5wv7dgnIgG8@public.gmane.org>
2014-09-12 11:48   ` [RFC 2/2] perf: Marker software event and ioctl Pawel Moll
2014-09-12 11:48     ` Pawel Moll
     [not found]     ` <1410522513-1045-3-git-send-email-pawel.moll-5wv7dgnIgG8@public.gmane.org>
2014-09-12 12:43       ` Christopher Covington
2014-09-12 12:43         ` Christopher Covington
     [not found]         ` <5412EA7A.9020807-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
2014-09-12 12:57           ` Pawel Moll
2014-09-12 12:57             ` Pawel Moll
2014-09-12 13:49             ` Arnaldo Carvalho de Melo
2014-09-12 13:49               ` Arnaldo Carvalho de Melo
     [not found]               ` <20140912134910.GG1801-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2014-09-12 13:58                 ` Pawel Moll
2014-09-12 13:58                   ` Pawel Moll
2014-09-12 16:19                   ` Arnaldo Carvalho de Melo
2014-09-12 16:19                     ` Arnaldo Carvalho de Melo
     [not found]                     ` <20140912161934.GJ1801-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2014-09-15 17:27                       ` Pawel Moll
2014-09-15 17:27                         ` Pawel Moll
2014-09-15 18:31                         ` Arnaldo Carvalho de Melo
2014-09-15 18:31                           ` Arnaldo Carvalho de Melo
     [not found]                           ` <20140915183101.GE11199-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2014-09-16 16:33                             ` Pawel Moll
2014-09-16 16:33                               ` Pawel Moll
2014-09-12 14:00             ` Christopher Covington [this message]
2014-09-12 14:00               ` Christopher Covington
2014-09-12 17:37       ` David Ahern
2014-09-12 17:37         ` David Ahern
     [not found]         ` <54132F63.1010401-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2014-09-12 20:44           ` Arnaldo Carvalho de Melo
2014-09-12 20:44             ` Arnaldo Carvalho de Melo
2014-09-14 15:43             ` David Ahern
     [not found]               ` <5415B790.5010607-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2014-09-15 17:18                 ` Pawel Moll
2014-09-15 17:18                   ` Pawel Moll
2014-09-16  7:44                 ` Ingo Molnar
2014-09-16  7:44                   ` Ingo Molnar
     [not found]                   ` <20140916074421.GA21295-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2014-09-16 16:37                     ` Pawel Moll
2014-09-16 16:37                       ` Pawel Moll
2014-09-16 17:58                       ` Ingo Molnar
2014-09-16 17:58                         ` Ingo Molnar

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