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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Tejun Heo <tj@kernel.org>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>,
	Ingo Molnar <mingo@redhat.com>,
	Sasha Levin <sasha.levin@oracle.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Michal Hocko <mhocko@kernel.org>,
	cgroups <cgroups@vger.kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	Vladimir Davydov <vdavydov@parallels.com>,
	kernel-team <kernel-team@fb.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH v4.4-rc7] sched: isolate task_struct bitfields according to synchronization domains
Date: Wed, 30 Dec 2015 12:10:12 -0800	[thread overview]
Message-ID: <CA+55aFx0WxoUPrOPaq3HxM+YUQQ0DPV-c3f8kE1ec7agERb_Lg@mail.gmail.com> (raw)
In-Reply-To: <20151230092337.GD3873@htj.duckdns.org>

On Wed, Dec 30, 2015 at 1:23 AM, Tejun Heo <tj@kernel.org> wrote:
>
> Peter, I took the patch and changed the bitfields to ulong.

I wouldn't expect the unsigned long part to matter, except for the
forced split with

   unsigned long :0;

itself.

Also, quite frankly, since this is basically very close to other
fields that are *not* unsigned longs, I'd really prefer to not
unnecessarily use a 64-bit field for three bits each.

So why not just do it with plain unsigned "int", and then maybe just
intersperse them with the other int-sized fields in that neighborhood.

I'm also wondering if we shouldn't just put the scheduler bits in the
"atomic_flags" thing instead?

                     Linus

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WARNING: multiple messages have this Message-ID (diff)
From: Linus Torvalds <torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
To: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Andrey Ryabinin
	<ryabinin.a.a-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	Ingo Molnar <mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	Sasha Levin <sasha.levin-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>,
	Andrew Morton
	<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
	Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>,
	Michal Hocko <mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	cgroups <cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	"linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org"
	<linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org>,
	Vladimir Davydov
	<vdavydov-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>,
	kernel-team <kernel-team-b10kYP2dOMg@public.gmane.org>,
	Dmitry Vyukov <dvyukov-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
	Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
Subject: Re: [PATCH v4.4-rc7] sched: isolate task_struct bitfields according to synchronization domains
Date: Wed, 30 Dec 2015 12:10:12 -0800	[thread overview]
Message-ID: <CA+55aFx0WxoUPrOPaq3HxM+YUQQ0DPV-c3f8kE1ec7agERb_Lg@mail.gmail.com> (raw)
In-Reply-To: <20151230092337.GD3873-piEFEHQLUPpN0TnZuCh8vA@public.gmane.org>

On Wed, Dec 30, 2015 at 1:23 AM, Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> wrote:
>
> Peter, I took the patch and changed the bitfields to ulong.

I wouldn't expect the unsigned long part to matter, except for the
forced split with

   unsigned long :0;

itself.

Also, quite frankly, since this is basically very close to other
fields that are *not* unsigned longs, I'd really prefer to not
unnecessarily use a 64-bit field for three bits each.

So why not just do it with plain unsigned "int", and then maybe just
intersperse them with the other int-sized fields in that neighborhood.

I'm also wondering if we shouldn't just put the scheduler bits in the
"atomic_flags" thing instead?

                     Linus

  reply	other threads:[~2015-12-30 20:10 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-09-13 18:59 [PATCH 1/2] memcg: flatten task_struct->memcg_oom Tejun Heo
2015-09-13 18:59 ` Tejun Heo
2015-09-13 19:00 ` [PATCH v3 2/2] memcg: punt high overage reclaim to return-to-userland path Tejun Heo
2015-09-15  7:47   ` Johannes Weiner
2015-09-15  7:47     ` Johannes Weiner
2015-09-15 15:53     ` Tejun Heo
2015-09-15 16:12       ` Johannes Weiner
2015-09-15 16:22         ` Tejun Heo
2015-09-15 16:22           ` Tejun Heo
2015-09-15 16:33           ` Johannes Weiner
2015-09-15 16:33             ` Johannes Weiner
2015-09-15  7:37 ` [PATCH 1/2] memcg: flatten task_struct->memcg_oom Johannes Weiner
2015-09-15  7:37   ` Johannes Weiner
2015-09-20 14:45 ` Sasha Levin
2015-09-20 14:45   ` Sasha Levin
2015-09-21 20:01   ` Tejun Heo
2015-09-21 20:01     ` Tejun Heo
2015-09-30 18:54     ` Tejun Heo
2015-09-30 18:54       ` Tejun Heo
2015-11-25 14:43     ` Peter Zijlstra
2015-11-25 14:43       ` Peter Zijlstra
2015-11-25 15:02       ` Peter Zijlstra
2015-11-25 15:02         ` Peter Zijlstra
2015-11-25 15:31         ` Andrey Ryabinin
2015-11-25 17:34           ` Dmitry Vyukov
2015-11-25 17:34             ` Dmitry Vyukov
2015-11-25 17:44           ` Peter Zijlstra
2015-12-11 16:25             ` Tejun Heo
2015-12-11 16:25               ` Tejun Heo
2015-12-15 19:22               ` Peter Zijlstra
2015-12-30  9:23                 ` [PATCH v4.4-rc7] sched: isolate task_struct bitfields according to synchronization domains Tejun Heo
2015-12-30 20:10                   ` Linus Torvalds [this message]
2015-12-30 20:10                     ` Linus Torvalds
2015-12-30 20:17                     ` Linus Torvalds
2015-12-30 20:41                     ` Tejun Heo
2015-12-30 20:41                       ` Tejun Heo
2015-12-30 20:43                       ` Linus Torvalds
2016-01-01  2:56                     ` [PATCH v4.4-rc7] sched: move sched lock synchronized bitfields in task_struct into ->atomic_flags Tejun Heo
2016-01-01  2:56                       ` Tejun Heo
2016-01-06 13:44                       ` Tejun Heo
2016-01-06 13:44                         ` Tejun Heo
2016-01-06 18:48         ` [tip:sched/core] sched/core: Fix unserialized r-m-w scribbling stuff tip-bot for Peter Zijlstra
2016-01-06 20:17           ` Tejun Heo

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