From: Kirill Tkhai <ktkhai@virtuozzo.com>
To: law@redhat.com, Peter Zijlstra <peterz@infradead.org>,
gcc-help@gcc.gnu.org
Cc: mingo@redhat.com, juri.lelli@redhat.com,
vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
linux-kernel@vger.kernel.org
Subject: Re: [Q] ld: Does LTO reorder ro variables in two files?
Date: Thu, 19 Dec 2019 18:30:56 +0300 [thread overview]
Message-ID: <15d40d09-3258-9b78-7120-bc708a429855@virtuozzo.com> (raw)
In-Reply-To: <db7acdee9a85ce5b74332b3869efa6c9e18bad9e.camel@redhat.com>
On 19.12.2019 18:21, Jeff Law wrote:
> On Thu, 2019-12-19 at 17:04 +0300, Kirill Tkhai wrote:
>> CC: gcc-help@gcc.gnu.org
>>
>> Hi, gcc guys,
>>
>> this thread starts here: https://lkml.org/lkml/2019/12/19/403
>>
>> There are two const variables:
>>
>> struct sched_class idle_sched_class
>> and
>> struct sched_class fair_sched_class,
>>
>> which are declared in two files idle.c and fair.c.
>>
>> 1)In Makefile the order is: idle.o fair.o
>> 2)the variables go to the same ro section
>> 3)there is no SORT(.*) keyword in linker script.
>>
>> Is it always true, that after linkage &idle_sched_class < &fair_sched_class?
> I certainly wouldn't depend on it. The first and most obvious problem
> is symbol sorting by the linker. Longer term I'd be worried about LTO
> reordering things.
>
> In the end I'm pretty sure it'd be well outside what I'd be comfortable
> depending on.
Ok, I'd be comfortable too :) Thanks for the clarification, Jeff.
next prev parent reply other threads:[~2019-12-19 15:31 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-19 12:39 [PATCH RFC] sched: Micro optimization in pick_next_task() and in check_preempt_curr() Kirill Tkhai
2019-12-19 13:12 ` Peter Zijlstra
2019-12-19 14:02 ` Peter Zijlstra
2019-12-19 14:25 ` Kirill Tkhai
2019-12-19 14:31 ` Kirill Tkhai
2019-12-19 14:43 ` Steven Rostedt
2019-12-19 14:46 ` Kirill Tkhai
2019-12-19 14:59 ` Steven Rostedt
2019-12-19 15:20 ` [PATCH v2] " Kirill Tkhai
2019-12-19 15:40 ` Steven Rostedt
2019-12-19 16:08 ` Kirill Tkhai
2019-12-19 16:22 ` Steven Rostedt
2019-12-19 20:16 ` Kirill Tkhai
2019-12-19 20:20 ` Steven Rostedt
2019-12-19 16:05 ` Steven Rostedt
2019-12-19 14:04 ` [Q] ld: Does LTO reorder ro variables in two files? Kirill Tkhai
2019-12-19 15:21 ` Jeff Law
2019-12-19 15:30 ` Kirill Tkhai [this message]
2019-12-19 15:45 ` Alexander Monakov
2019-12-19 16:08 ` Kirill Tkhai
2019-12-19 13:50 ` [PATCH RFC] sched: Micro optimization in pick_next_task() and in check_preempt_curr() Steven Rostedt
2019-12-19 13:53 ` Kirill Tkhai
2019-12-19 13:53 ` Peter Zijlstra
2020-06-25 11:53 ` [tip: sched/core] sched: Force the address order of each sched class descriptor tip-bot2 for Steven Rostedt (VMware)
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