From: Eugene Rozenfeld <Eugene.Rozenfeld@microsoft.com>
To: Sam James <sam@gentoo.org>, Richard Biener <richard.guenther@gmail.com>
Cc: "gcc-patches@gcc.gnu.org" <gcc-patches@gcc.gnu.org>
Subject: RE: [EXTERNAL] Re: [PATCH] Collect both user and kernel events for autofdo tests and autoprofiledbootstrap
Date: Fri, 30 Jun 2023 21:44:19 +0000 [thread overview]
Message-ID: <DS7PR21MB3479A2D2BED61B40252B3A55912AA@DS7PR21MB3479.namprd21.prod.outlook.com> (raw)
In-Reply-To: <87v8f51g0h.fsf@gentoo.org>
I don't run this with elevated privileges but I set /proc/sys/kernel/kptr_restrict to 0. Setting that does require elevated privileges.
If that's not acceptable, the only fix I can think of is to make that event mapping threshold percentage a parameter to create_gcov and pass something low enough. 80% instead of the current threshold of 95% should work, although it's a bit fragile.
Eugene
-----Original Message-----
From: Sam James <sam@gentoo.org>
Sent: Friday, June 30, 2023 1:59 AM
To: Richard Biener <richard.guenther@gmail.com>
Cc: Eugene Rozenfeld <Eugene.Rozenfeld@microsoft.com>; gcc-patches@gcc.gnu.org
Subject: [EXTERNAL] Re: [PATCH] Collect both user and kernel events for autofdo tests and autoprofiledbootstrap
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Richard Biener via Gcc-patches <gcc-patches@gcc.gnu.org> writes:
> On Fri, Jun 30, 2023 at 7:28 AM Eugene Rozenfeld via Gcc-patches
> <gcc-patches@gcc.gnu.org> wrote:
>>
>> When we collect just user events for autofdo with lbr we get some
>> events where branch sources are kernel addresses and branch targets
>> are user addresses. Without kernel MMAP events create_gcov can't make
>> sense of kernel addresses. Currently create_gcov fails if it can't
>> map at least 95% of events. We sometimes get below this threshold with just user events. The change is to collect both user events and kernel events.
>
> Does this require elevated privileges? Can we instead "fix" create_gcov here?
Right, requiring privileges for this is going to be a no-go for a lot of builders. In a distro context, for example, it means we can't consider autofdo at all.
next prev parent reply other threads:[~2023-06-30 21:44 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-30 5:27 Eugene Rozenfeld
2023-06-30 8:51 ` Richard Biener
2023-06-30 8:59 ` Sam James
2023-06-30 21:44 ` Eugene Rozenfeld [this message]
2023-06-30 22:05 ` [EXTERNAL] " Eugene Rozenfeld
2023-07-03 7:46 ` Richard Biener
2023-07-05 21:15 ` Eugene Rozenfeld
2023-07-06 6:23 ` Richard Biener
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