From: "Jan Beulich" <jbeulich@suse.com>
To: boris.ostrovsky@oracle.com
Cc: tim@xen.org, sstabellini@kernel.org, wei.liu2@citrix.com,
George.Dunlap@eu.citrix.com, andrew.cooper3@citrix.com,
ian.jackson@eu.citrix.com, xen-devel@lists.xen.org
Subject: Re: [PATCH v6 5/8] spinlock: Introduce spin_lock_cb()
Date: Mon, 07 Aug 2017 01:32:28 -0600 [thread overview]
Message-ID: <5988178C0200007800103857@prv-mh.provo.novell.com> (raw)
In-Reply-To: <1501866346-9774-6-git-send-email-boris.ostrovsky@oracle.com>
>>> Boris Ostrovsky <boris.ostrovsky@oracle.com> 08/04/17 7:03 PM >>>
>While waiting for a lock we may want to periodically run some
>code. This code may, for example, allow the caller to release
>resources held by it that are no longer needed in the critical
>section protected by the lock.
>
>Specifically, this feature will be needed by scrubbing code where
>the scrubber, while waiting for heap lock to merge back clean
>pages, may be requested by page allocator (which is currently
>holding the lock) to abort merging and release the buddy page head
>that the allocator wants.
>
>We could use spin_trylock() but since it doesn't take lock ticket
>it may take long time until the lock is taken. Instead we add
>spin_lock_cb() that allows us to grab the ticket and execute a
>callback while waiting. This callback is executed on every iteration
>of the spinlock waiting loop.
>
>Since we may be sleeping in the lock until it is released we need a
>mechanism that will make sure that the callback has a chance to run.
>We add spin_lock_kick() that will wake up the waiter.
>
>Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
As previously expressed I'm not overly happy with this, but I also can't
see any good alternative for the use of it in the following patch(es).
Short of any other REST maintainer having voiced any opinion (iirc),
this is
Acked-by: Jan Beulich <jbeulich@suse.com>
Jan
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next prev parent reply other threads:[~2017-08-07 7:32 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-04 17:05 [PATCH v6 0/8] Memory scrubbing from idle loop Boris Ostrovsky
2017-08-04 17:05 ` [PATCH v6 1/8] mm: Place unscrubbed pages at the end of pagelist Boris Ostrovsky
2017-08-06 17:41 ` Jan Beulich
2017-08-07 14:12 ` Boris Ostrovsky
2017-08-07 14:37 ` Jan Beulich
2017-08-07 14:55 ` Boris Ostrovsky
2017-08-07 15:28 ` Jan Beulich
2017-08-07 10:45 ` Julien Grall
2017-08-07 14:46 ` Boris Ostrovsky
2017-08-07 15:23 ` Julien Grall
2017-08-07 16:57 ` Boris Ostrovsky
2017-08-07 17:01 ` Julien Grall
2017-08-07 17:20 ` Boris Ostrovsky
2017-08-04 17:05 ` [PATCH v6 2/8] mm: Extract allocation loop from alloc_heap_pages() Boris Ostrovsky
2017-08-06 17:42 ` Jan Beulich
2017-08-04 17:05 ` [PATCH v6 3/8] mm: Scrub pages in alloc_heap_pages() if needed Boris Ostrovsky
2017-08-04 17:05 ` [PATCH v6 4/8] mm: Scrub memory from idle loop Boris Ostrovsky
2017-08-07 7:29 ` Jan Beulich
2017-08-07 14:05 ` Dario Faggioli
2017-08-04 17:05 ` [PATCH v6 5/8] spinlock: Introduce spin_lock_cb() Boris Ostrovsky
2017-08-07 7:32 ` Jan Beulich [this message]
2017-08-04 17:05 ` [PATCH v6 6/8] mm: Keep heap accessible to others while scrubbing Boris Ostrovsky
2017-08-07 7:50 ` Jan Beulich
2017-08-04 17:05 ` [PATCH v6 7/8] mm: Print number of unscrubbed pages in 'H' debug handler Boris Ostrovsky
2017-08-04 17:05 ` [PATCH v6 8/8] mm: Make sure pages are scrubbed Boris Ostrovsky
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