linux-kernel - Re: Very slow SYS_io

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Message-ID: <4c5819ce-72cb-2ee3-06b9-8c3d0a11a0aa@gblabs.co.uk>
Date:   Mon, 23 Jul 2018 16:16:34 +0100
From:   Alex Richman <alex.r@...abs.co.uk>
To:     Jeff Moyer <jmoyer@...hat.com>
Cc:     linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: Very slow SYS_io_destroy()

Thanks for the response.  I'm running 4.4.123-1 from Gentoo.  It also 
happens on 4.4.87-r1.

Cheers,
- Alex.

On 23/07/18 16:13, Jeff Moyer wrote:
> Alex Richman <alex.r@...abs.co.uk> writes:
>
>> Hi,
>>
>> I'm seeing some weirdness with AIO, specifically SYS_io_destroy() is
>> taking upwards of ~100000 microseconds (~100 miliseconds) per call.
>> How long is that call expected to take?  I can see from the source
> Well, it waits for an RCU grace period.  I would not expect that to take
> 100ms, though.  What kernel version is this?
>
> -Jeff

-- 
Alex Richman
alex.r@...abs.co.uk
Engineering
Tel:+44 (0)118 455 5000
www.gblabs.com