From: Peter Zijlstra <peterz@infradead.org>
To: Trond Myklebust <trondmy@hammerspace.com>
Cc: "neilb@suse.de" <neilb@suse.de>,
"juri.lelli@redhat.com" <juri.lelli@redhat.com>,
"mingo@redhat.com" <mingo@redhat.com>,
"jiangshanlai@gmail.com" <jiangshanlai@gmail.com>,
"tj@kernel.org" <tj@kernel.org>,
"mhocko@suse.com" <mhocko@suse.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"vincent.guittot@linaro.org" <vincent.guittot@linaro.org>
Subject: Re: [PATCH rfc] workqueue: honour cond_resched() more effectively.
Date: Mon, 9 Nov 2020 15:20:16 +0100 [thread overview]
Message-ID: <20201109142016.GK2611@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <aec65c71c09e803285688d5974193a98b4422428.camel@hammerspace.com>
On Mon, Nov 09, 2020 at 01:50:40PM +0000, Trond Myklebust wrote:
> On Mon, 2020-11-09 at 09:00 +0100, Peter Zijlstra wrote:
> > I'm thinking the real problem is that you're abusing workqueues. Just
> > don't stuff so much work into it that this becomes a problem. Or
> > rather,
> > if you do, don't lie to it about it.
>
> If we can't use workqueues to call iput_final() on an inode, then what
> is the point of having them at all?
Running short stuff, apparently.
> Neil's use case is simply a file that has managed to accumulate a
> seriously large page cache, and is therefore taking a long time to
> complete the call to truncate_inode_pages_final(). Are you saying we
> have to allocate a dedicated thread for every case where this happens?
I'm not saying anything, but you're trying to wreck the scheduler
because of a workqueue 'feature'. The 'new' workqueues limit concurrency
by design, if you're then relying on concurrency for things, you're
using it wrong.
I really don't know what the right answer is here, but I thoroughly hate
the one proposed.
next prev parent reply other threads:[~2020-11-09 14:20 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-09 2:54 [PATCH rfc] workqueue: honour cond_resched() more effectively NeilBrown
2020-11-09 7:50 ` Michal Hocko
2020-11-09 8:00 ` Peter Zijlstra
2020-11-09 13:50 ` Trond Myklebust
2020-11-09 14:01 ` tj
2020-11-09 14:11 ` Trond Myklebust
2020-11-09 16:10 ` tj
2020-11-17 22:16 ` NeilBrown
[not found] ` <20201118025820.307-1-hdanton@sina.com>
2020-11-18 5:11 ` NeilBrown
[not found] ` <20201118055108.358-1-hdanton@sina.com>
2020-11-19 23:07 ` NeilBrown
2020-12-02 20:20 ` tj
[not found] ` <20201120025953.607-1-hdanton@sina.com>
2020-11-20 4:33 ` NeilBrown
[not found] ` <20201126100646.1790-1-hdanton@sina.com>
2020-11-26 23:44 ` NeilBrown
2020-11-19 23:23 ` NeilBrown
2020-11-25 12:36 ` tj
2020-11-26 23:30 ` NeilBrown
2020-11-09 14:20 ` Peter Zijlstra [this message]
2020-11-10 2:26 ` NeilBrown
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