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From: Tim Chen <tim.c.chen@linux.intel.com>
To: Linus Torvalds <torvalds@linux-foundation.org>,
	David Howells <dhowells@redhat.com>,
	Kan Liang <kan.liang@intel.com>
Cc: Casey Schaufler <casey@schaufler-ca.com>,
	Stephen Smalley <sds@tycho.nsa.gov>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Nicolas Dichtel <nicolas.dichtel@6wind.com>,
	raven@themaw.net, Christian Brauner <christian@brauner.io>,
	keyrings@vger.kernel.org, linux-usb@vger.kernel.org,
	linux-block <linux-block@vger.kernel.org>,
	LSM List <linux-security-module@vger.kernel.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Linux API <linux-api@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH 02/21] Add a prelocked wake-up
Date: Wed, 16 Oct 2019 10:02:24 -0700	[thread overview]
Message-ID: <533ca3c5-1592-e59b-eafe-bc4a352a442d@linux.intel.com> (raw)
In-Reply-To: <CAHk-=whiz1sHXu8SVZKEC2dup=r5JMrftPtEt6ff9Ea8dyH8yQ@mail.gmail.com>

On 10/15/19 3:14 PM, Linus Torvalds wrote:
> On Tue, Oct 15, 2019 at 2:48 PM David Howells <dhowells@redhat.com> wrote:
>>
>> Add a wakeup call for a case whereby the caller already has the waitqueue
>> spinlock held.
> 
> That naming is crazy.
> 
> We already have helper functions like this, and they are just called
> "wake_up_locked()".
> 
> So the "prelocked" naming is just odd. Make it be
> wake_up_interruptible_sync_poll_locked().
> 
> The helper function should likely be
> 
>   void __wake_up_locked_sync_key(struct wait_queue_head *wq_head,
> unsigned int mode, void *key)
>   {
>         __wake_up_common(wq_head, mode, 1, WF_SYNC, key, NULL);
>   }
>   EXPORT_SYMBOL_GPL(__wake_up_locked_sync_key);
> 
> to match the other naming patterns there.
> 
> [ Unrelated ]
> 
> Looking at that mess of functions, I also wonder if we should try to
> just remove the bookmark code again. It was cute, and it was useful,
> but I think the problem with the page lock list may have been fixed by
> commit 9a1ea439b16b ("mm: put_and_wait_on_page_locked() while page is
> migrated") which avoids the retry condition with
> migrate_page_move_mapping().
> 
> Tim/Kan? Do you have the problematic load still?
> 

Unfortunately, we do not have ready access to that problematic load
which was run by a customer on 8 socket system.  They were not
willing to give the workload to us, and have not responded to my
request to rerun their load with commit 9a1ea439b16b.

The commit greatly reduced migration failures with concurrent page faulting.
And successful migrations could have prevented the big
pile up of waiters faulting and waiting on the page, which was the
problem the bookmark code was trying to solve.

So I also tend to think that the problem should have been resolved.
But unfortunately I don't have a ready workload to confirm.

Tim


  reply	other threads:[~2019-10-16 17:02 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-15 21:47 [RFC PATCH 00/21] pipe: Keyrings, Block and USB notifications David Howells
2019-10-15 21:47 ` [RFC PATCH 01/21] pipe: Reduce #inclusion of pipe_fs_i.h David Howells
2019-10-15 21:48 ` [RFC PATCH 02/21] Add a prelocked wake-up David Howells
2019-10-15 22:14   ` Linus Torvalds
2019-10-16 17:02     ` Tim Chen [this message]
2019-10-15 22:33   ` David Howells
2019-10-16 14:26   ` David Howells
2019-10-16 15:31     ` Linus Torvalds
2019-10-15 21:48 ` [RFC PATCH 03/21] pipe: Use head and tail pointers for the ring, not cursor and length David Howells
2019-10-16  7:46   ` Rasmus Villemoes
2019-10-17 10:53   ` David Howells
2019-10-15 21:48 ` [RFC PATCH 04/21] pipe: Advance tail pointer inside of wait spinlock in pipe_read() David Howells
2019-10-15 21:48 ` [RFC PATCH 05/21] pipe: Conditionalise wakeup " David Howells
2019-10-15 21:48 ` [RFC PATCH 06/21] pipe: Rearrange sequence in pipe_write() to preallocate slot David Howells
2019-10-15 21:48 ` [RFC PATCH 07/21] pipe: Remove redundant wakeup from pipe_write() David Howells
2019-10-15 21:49 ` [RFC PATCH 08/21] pipe: Check for ring full inside of the spinlock in pipe_write() David Howells
2019-10-15 22:20   ` Linus Torvalds
2019-10-15 21:49 ` [RFC PATCH 09/21] uapi: General notification queue definitions David Howells
2019-10-15 21:49 ` [RFC PATCH 10/21] security: Add hooks to rule on setting a watch David Howells
2019-10-15 21:49 ` [RFC PATCH 11/21] security: Add a hook for the point of notification insertion David Howells
2019-10-15 21:49 ` [RFC PATCH 12/21] pipe: Add general notification queue support David Howells
2019-10-15 21:49 ` [RFC PATCH 13/21] keys: Add a notification facility David Howells
2019-10-15 21:49 ` [RFC PATCH 14/21] Add sample notification program David Howells
2019-10-15 21:50 ` [RFC PATCH 15/21] pipe: Allow buffers to be marked read-whole-or-error for notifications David Howells
2019-10-15 21:50 ` [RFC PATCH 16/21] pipe: Add notification lossage handling David Howells
2019-10-15 21:50 ` [RFC PATCH 17/21] Add a general, global device notification watch list David Howells
2019-10-15 21:50 ` [RFC PATCH 18/21] block: Add block layer notifications David Howells
2019-10-15 21:50 ` [RFC PATCH 19/21] usb: Add USB subsystem notifications David Howells
2019-10-15 21:50 ` [RFC PATCH 20/21] selinux: Implement the watch_key security hook David Howells
2019-10-15 21:50 ` [RFC PATCH 21/21] smack: Implement the watch_key and post_notification hooks David Howells
2019-10-15 22:11 ` [RFC PATCH 00/21] pipe: Keyrings, Block and USB notifications James Morris
2019-10-15 22:32 ` Linus Torvalds

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