From: Andi Kleen <andi@firstfloor.org>
To: Jeff Law <law@redhat.com>
Cc: "Nathan Sidwell" <nathan@acm.org>,
"Martin Liška" <mliska@suse.cz>,
"Andi Kleen" <andi@firstfloor.org>,
gcc-patches@gcc.gnu.org, jh@suse.cz
Subject: Re: [PATCH] Set -fprofile-update=atomic when -pthread is present
Date: Mon, 03 Oct 2016 17:52:00 -0000 [thread overview]
Message-ID: <20161003175253.GH5871@two.firstfloor.org> (raw)
In-Reply-To: <73a8abe7-3d49-4be0-54ba-e2de8af71b73@redhat.com>
> >>I would to somehow resolve the discussion related to default value
> >>selection.
> >>Is the prevailing consensus that we should set -fprofile-update=atomic
> >>when
> >>-pthread is set? If so, I'll prepare a patch. I tend to do it this way.
> >
> >This is my preference.
> Likewise.
I still think it shouldn't be default even with -pthread because it could dramatically
degrade performance in these cases. People likely have -pthread in their Makefiles
without realizing it. Such changes should be explict opt-in.
Often severe performance decreases lead to incorrectness in practice
("is now too slow to finish training workload in rebuild cycle")
-Andi
next prev parent reply other threads:[~2016-10-03 17:52 UTC|newest]
Thread overview: 95+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-01 8:50 [PATCH 0/4] Various GCOV/PGO improvements marxin
2016-08-01 8:49 ` [PATCH 3/4] Fix typo in gcov.texi marxin
2016-08-01 8:50 ` [PATCH 2/4] Remove __gcov_indirect_call_profiler marxin
2016-08-01 8:50 ` [PATCH 1/4] Cherry-pick fprofile-generate-atomic from google/gcc-4_9 branch marxin
2016-08-01 12:22 ` Nathan Sidwell
2016-08-01 13:29 ` Martin Liška
2016-08-04 14:48 ` Nathan Sidwell
2016-08-04 15:34 ` Martin Liška
2016-08-04 16:43 ` Nathan Sidwell
2016-08-04 17:03 ` Nathan Sidwell
2016-08-05 8:55 ` Martin Liška
2016-08-05 12:38 ` Nathan Sidwell
2016-08-05 12:48 ` Martin Liška
2016-08-05 13:14 ` Nathan Sidwell
2016-08-05 13:43 ` Martin Liška
2016-08-08 13:59 ` [PATCH 5/N] Add new *_atomic counter update function, (-fprofile-update=atomic) Martin Liška
2016-08-08 15:24 ` Nathan Sidwell
2016-08-08 16:51 ` Martin Liška
2016-08-08 17:03 ` Martin Liška
2016-08-09 12:36 ` Nathan Sidwell
2016-08-08 16:56 ` [PATCH] Fix POW2 histogram Martin Liška
2016-08-09 8:41 ` [PATCH 2/N] Fix usage of " Martin Liška
2016-08-09 12:37 ` Nathan Sidwell
2016-08-09 12:34 ` [PATCH] Fix " Nathan Sidwell
2016-08-09 11:24 ` [PATCH] Set -fprofile-update=atomic when -pthread is present Martin Liška
2016-08-09 12:40 ` Nathan Sidwell
2016-08-09 19:04 ` Andi Kleen
2016-08-12 13:31 ` Martin Liška
2016-08-18 3:16 ` Jeff Law
2016-08-18 11:02 ` Nathan Sidwell
2016-08-18 15:51 ` Andi Kleen
2016-08-18 15:53 ` Jeff Law
2016-10-03 12:13 ` Martin Liška
2016-10-03 12:26 ` Nathan Sidwell
2016-10-03 16:46 ` Jeff Law
2016-10-03 17:52 ` Andi Kleen [this message]
2016-10-04 12:05 ` Martin Liška
2016-10-05 17:54 ` Jeff Law
2016-10-13 15:34 ` [PATCH] Introduce -fprofile-update=maybe-atomic Martin Liška
2016-10-31 9:13 ` Martin Liška
2016-11-10 13:19 ` Martin Liška
2016-11-10 15:43 ` Nathan Sidwell
2016-11-10 15:55 ` David Edelsohn
2016-11-10 16:18 ` Nathan Sidwell
2016-11-10 15:58 ` Martin Liška
2016-11-10 16:17 ` David Edelsohn
2016-11-10 16:24 ` Martin Liška
2016-11-10 17:31 ` Nathan Sidwell
2016-11-11 10:48 ` Martin Liška
2016-11-11 15:11 ` Nathan Sidwell
2016-11-10 16:14 ` Nathan Sidwell
2016-11-10 16:16 ` David Edelsohn
2016-08-18 15:54 ` [PATCH] Set -fprofile-update=atomic when -pthread is present Jakub Jelinek
2016-08-18 16:06 ` Richard Biener
2016-09-07 11:41 ` Martin Liška
[not found] ` <CAFiYyc0UaSzXhZmyG9QRkHGT4JFowxBfE2yb-NvXE=hR1xafdA@mail.gmail.com>
2016-09-15 10:18 ` [RFC] Speed-up -fprofile-update=atomic Martin Liška
2016-10-04 9:45 ` Richard Biener
2016-10-12 13:53 ` Martin Liška
2016-10-13 9:43 ` Richard Biener
2016-10-17 11:47 ` Martin Liška
[not found] ` <CAFiYyc3eDT4g926PPZuktz5fEW=k-PibAcxhigx4GBcxoXNJFQ@mail.gmail.com>
2016-10-24 12:09 ` Martin Liška
[not found] ` <CAFiYyc1tSdTdqqkHcMp+dgE43+8tHL6kY8E07TCHoZBeUT-ggQ@mail.gmail.com>
2016-10-25 14:32 ` Martin Liška
2016-10-26 9:29 ` Richard Biener
2016-10-26 9:32 ` Richard Biener
2016-08-18 16:04 ` [PATCH] Set -fprofile-update=atomic when -pthread is present Richard Biener
2016-08-10 12:57 ` [PATCH 1/4] Cherry-pick fprofile-generate-atomic from google/gcc-4_9 branch Nathan Sidwell
2016-08-13 12:14 ` [BUILDROBOT] avr broken (was: [PATCH 1/4] Cherry-pick fprofile-generate-atomic from google/gcc-4_9 branch) Jan-Benedict Glaw
[not found] ` <4455937b-eba7-fe66-fe1a-3172567dd1e4@suse.cz>
2016-08-16 13:36 ` [BUILDROBOT] avr broken Nathan Sidwell
[not found] ` <617e8799-b7db-fefd-b3a3-842e9a7decfd@suse.cz>
2016-08-16 14:31 ` Nathan Sidwell
2016-08-16 17:05 ` Jan-Benedict Glaw
2016-08-16 18:26 ` Nathan Sidwell
2016-08-17 7:21 ` Denis Chertykov
2016-08-17 7:22 ` Martin Liška
2016-08-17 8:11 ` Jan-Benedict Glaw
2016-08-16 12:56 ` [PATCH] Detect whether target can use -fprofile-update=atomic Martin Liška
2016-08-16 14:31 ` Nathan Sidwell
2016-09-06 10:57 ` Martin Liška
2016-09-06 11:17 ` David Edelsohn
2016-09-06 12:15 ` Nathan Sidwell
2016-09-06 12:39 ` Jakub Jelinek
2016-09-06 12:43 ` David Edelsohn
2016-09-06 12:41 ` David Edelsohn
2016-09-06 12:51 ` Martin Liška
2016-09-06 13:13 ` Jakub Jelinek
2016-09-06 13:15 ` Martin Liška
2016-09-06 13:45 ` Jakub Jelinek
2016-09-06 13:50 ` Martin Liška
2016-09-06 14:06 ` Jakub Jelinek
2016-09-07 7:52 ` Christophe Lyon
2016-09-07 9:35 ` Martin Liška
2016-09-07 16:06 ` Christophe Lyon
2016-09-12 20:20 ` Jeff Law
2016-09-29 8:31 ` Rainer Orth
2016-08-01 8:50 ` [PATCH 4/4] Add tests for __gcov_dump and __gcov_reset marxin
2016-08-01 12:11 ` [PATCH 0/4] Various GCOV/PGO improvements Nathan Sidwell
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