From: Michal Hocko <mhocko@suse.com>
To: NeilBrown <neilb@suse.de>
Cc: Uladzislau Rezki <urezki@gmail.com>,
Linux Memory Management List <linux-mm@kvack.org>,
Dave Chinner <david@fromorbit.com>,
Andrew Morton <akpm@linux-foundation.org>,
Christoph Hellwig <hch@infradead.org>,
linux-fsdevel@vger.kernel.org,
LKML <linux-kernel@vger.kernel.org>,
Ilya Dryomov <idryomov@gmail.com>,
Jeff Layton <jlayton@kernel.org>
Subject: Re: [RFC 2/3] mm/vmalloc: add support for __GFP_NOFAIL
Date: Thu, 21 Oct 2021 12:27:28 +0200 [thread overview]
Message-ID: <YXFAkFx8PCCJC0Iy@dhcp22.suse.cz> (raw)
In-Reply-To: <163481121586.17149.4002493290882319236@noble.neil.brown.name>
On Thu 21-10-21 21:13:35, Neil Brown wrote:
> On Thu, 21 Oct 2021, Uladzislau Rezki wrote:
> > On Wed, Oct 20, 2021 at 05:00:28PM +0200, Uladzislau Rezki wrote:
> > > >
> > > > On Wed 20-10-21 16:29:14, Uladzislau Rezki wrote:
> > > > > On Wed, Oct 20, 2021 at 4:06 PM Michal Hocko <mhocko@suse.com> wrote:
> > > > [...]
> > > > > > As I've said I am OK with either of the two. Do you or anybody have any
> > > > > > preference? Without any explicit event to wake up for neither of the two
> > > > > > is more than just an optimistic retry.
> > > > > >
> > > > > From power perspective it is better to have a delay, so i tend to say
> > > > > that delay is better.
> > > >
> > > > I am a terrible random number generator. Can you give me a number
> > > > please?
> > > >
> > > Well, we can start from one jiffy so it is one timer tick: schedule_timeout(1)
> > >
> > A small nit, it is better to replace it by the simple msleep() call: msleep(jiffies_to_msecs(1));
>
> I disagree. I think schedule_timeout_uninterruptible(1) is the best
> wait to sleep for 1 ticl
>
> msleep() contains
> timeout = msecs_to_jiffies(msecs) + 1;
> and both jiffies_to_msecs and msecs_to_jiffies might round up too.
> So you will sleep for at least twice as long as you asked for, possible
> more.
That was my thinking as well. Not to mention jiffies_to_msecs just to do
msecs_to_jiffies right after which seems like a pointless wasting of
cpu cycle. But maybe I was missing some other reasons why msleep would
be superior.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2021-10-21 10:27 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-18 11:47 [RFC 0/3] extend vmalloc support for constrained allocations Michal Hocko
2021-10-18 11:47 ` [RFC 1/3] mm/vmalloc: alloc GFP_NO{FS,IO} for vmalloc Michal Hocko
2021-10-19 0:44 ` NeilBrown
2021-10-19 6:59 ` Michal Hocko
2021-10-18 11:47 ` [RFC 2/3] mm/vmalloc: add support for __GFP_NOFAIL Michal Hocko
2021-10-18 16:48 ` Michal Hocko
2021-10-19 11:06 ` Uladzislau Rezki
2021-10-19 11:52 ` Michal Hocko
2021-10-19 19:46 ` Uladzislau Rezki
2021-10-20 8:25 ` Michal Hocko
2021-10-20 9:18 ` Michal Hocko
2021-10-20 13:54 ` Uladzislau Rezki
2021-10-20 14:06 ` Michal Hocko
2021-10-20 14:29 ` Uladzislau Rezki
2021-10-20 14:53 ` Michal Hocko
2021-10-20 15:00 ` Uladzislau Rezki
2021-10-20 19:24 ` Uladzislau Rezki
2021-10-21 8:56 ` Michal Hocko
2021-10-21 10:13 ` NeilBrown
2021-10-21 10:27 ` Michal Hocko [this message]
2021-10-21 10:40 ` Uladzislau Rezki
2021-10-21 22:49 ` NeilBrown
2021-10-22 8:18 ` Michal Hocko
2021-10-25 9:48 ` Uladzislau Rezki
2021-10-25 11:20 ` Michal Hocko
2021-10-25 14:30 ` Uladzislau Rezki
2021-10-25 14:56 ` Michal Hocko
2021-10-25 23:50 ` NeilBrown
2021-10-26 7:16 ` Michal Hocko
2021-10-26 10:24 ` NeilBrown
2021-10-26 14:25 ` Uladzislau Rezki
2021-10-26 14:43 ` Michal Hocko
2021-10-26 15:40 ` Uladzislau Rezki
2021-10-20 8:25 ` [PATCH] mm/vmalloc: be more explicit about supported gfp flags Michal Hocko
2021-10-18 11:47 ` [RFC 3/3] mm: allow !GFP_KERNEL allocations for kvmalloc Michal Hocko
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