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From: Jessica Yu <jeyu@kernel.org>
To: Prarit Bhargava <prarit@redhat.com>
Cc: linux-kernel@vger.kernel.org,
	Heiko Carstens <heiko.carstens@de.ibm.com>,
	David Arcari <darcari@redhat.com>
Subject: Re: [PATCH v3] kernel/module: Reschedule while waiting for modules to finish loading
Date: Thu, 2 May 2019 11:48:14 +0200	[thread overview]
Message-ID: <20190502094813.GA6690@linux-8ccs> (raw)
In-Reply-To: <90e18809-2b70-52d8-00b3-9c16768db9ad@redhat.com>

+++ Prarit Bhargava [01/05/19 17:26 -0400]:
>
>
>On 4/30/19 6:22 PM, Prarit Bhargava wrote:
>> On a s390 z14 LAR with 2 cpus about stalls about 3% of the time while
>> loading the s390_trng.ko module.
>>
>> Add a reschedule point to the loop that waits for modules to complete
>> loading.
>>
>> v3: cleanup Fixes line.
>
>Jessica, even with this additional patch there appears to be some other issues
>in the module code that are causing significant delays in boot up on large
>systems.

Is this limited to only s390? Or are you seeing this on other arches
as well? And is it limited to specific modules (like s390_trng)?

>Please revert these fixes from linux-next & modules-next.  I apologize for the
>extra work but I think it is for the best until I come up with a more complete &
>better tested patch.

Sure, then I will revert this patch and the other one as well
("modules: Only return -EEXIST for modules that have finished
loading").

>FWIW, the logic in the original patch is correct.  It's just that there's, as
>Heiko discovered, some poor scheduling, etc., that is impacting the module
>loading code after these changes.

I am really curious to see what these performance regressions look
like :/ Please update us when you find out more.

>Again, my apologies,

No problem! Thanks again.

Jessica


  reply	other threads:[~2019-05-02  9:48 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-30 22:22 Prarit Bhargava
2019-05-01  7:49 ` Jessica Yu
2019-05-01 21:26 ` Prarit Bhargava
2019-05-02  9:48   ` Jessica Yu [this message]
2019-05-02 12:41     ` Prarit Bhargava
2019-05-02 17:46       ` Prarit Bhargava
2019-05-10 18:40         ` Barret Rhoden
2019-05-10 18:42           ` [PATCH] modules: fix livelock in add_unformed_module() Barret Rhoden
2019-05-13 11:23             ` Prarit Bhargava
2019-05-13 14:37               ` Barret Rhoden
2019-05-22 17:08                 ` Prarit Bhargava
2019-05-28 14:30                   ` Prarit Bhargava
2019-05-28 14:47                     ` Jessica Yu

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