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From: "Jan Beulich" <JBeulich@suse.com>
To: Boris Ostrovsky <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 v2 6/9] spinlock: Introduce spin_lock_cb()
Date: Thu, 13 Apr 2017 09:46:02 -0600	[thread overview]
Message-ID: <58EFB95A0200007800150DD3@prv-mh.provo.novell.com> (raw)
In-Reply-To: <1491238256-5517-7-git-send-email-boris.ostrovsky@oracle.com>

>>> On 03.04.17 at 18:50, <boris.ostrovsky@oracle.com> wrote:
> While waiting for a lock we may want to periodically run some
> code. We could use spin_trylock() but since it doesn't take lock
> ticket it may take a long time until the lock is taken.
> 
> Add spin_lock_cb() that allows us to execute a callback while waiting.

You don't add any user(s) of this new interface and you also don't
outline under what conditions you think using this might be a good
idea. On that basis I don't think this makes much sense. I am
particularly worried of undue latencies use of this function may
incur.

> Also add spin_lock_kick() that will wake up the waiters.

Same here - I can't even seem to guess what use you intend this to
have.

Nevertheless the code itself looks okay.

Jan


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  reply	other threads:[~2017-04-13 15:46 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-03 16:50 [PATCH v2 0/9] Memory scrubbing from idle loop Boris Ostrovsky
2017-04-03 16:50 ` [PATCH v2 1/9] mm: Separate free page chunk merging into its own routine Boris Ostrovsky
2017-04-04 11:16   ` Jan Beulich
2017-04-04 13:48     ` Boris Ostrovsky
2017-04-04 14:01       ` Jan Beulich
2017-04-04 14:23         ` Boris Ostrovsky
2017-04-03 16:50 ` [PATCH v2 2/9] mm: Place unscrubbed pages at the end of pagelist Boris Ostrovsky
2017-04-04 14:46   ` Jan Beulich
2017-04-04 15:14     ` Boris Ostrovsky
2017-04-04 15:29       ` Jan Beulich
2017-04-04 15:39         ` Boris Ostrovsky
2017-04-04 15:50           ` Jan Beulich
2017-04-04 16:22             ` Boris Ostrovsky
2017-04-03 16:50 ` [PATCH v2 3/9] mm: Scrub pages in alloc_heap_pages() if needed Boris Ostrovsky
2017-04-03 16:50 ` [PATCH v2 4/9] mm: Scrub memory from idle loop Boris Ostrovsky
2017-04-12 16:11   ` Jan Beulich
2017-04-03 16:50 ` [PATCH v2 5/9] mm: Do not discard already-scrubbed pages softirqs are pending Boris Ostrovsky
2017-04-13 15:41   ` Jan Beulich
2017-04-13 16:46     ` Boris Ostrovsky
2017-04-03 16:50 ` [PATCH v2 6/9] spinlock: Introduce spin_lock_cb() Boris Ostrovsky
2017-04-13 15:46   ` Jan Beulich [this message]
2017-04-13 16:55     ` Boris Ostrovsky
2017-04-18  6:49       ` Jan Beulich
2017-04-18 12:32         ` Boris Ostrovsky
2017-04-18 12:43           ` Jan Beulich
2017-04-18 13:14             ` Boris Ostrovsky
2017-04-03 16:50 ` [PATCH v2 7/9] mm: Keep pages available for allocation while scrubbing Boris Ostrovsky
2017-04-13 15:59   ` Jan Beulich
2017-04-03 16:50 ` [PATCH v2 8/9] mm: Print number of unscrubbed pages in 'H' debug handler Boris Ostrovsky
2017-04-03 16:50 ` [PATCH v2 9/9] mm: Make sure pages are scrubbed Boris Ostrovsky
2017-04-04 15:21 ` [PATCH v2 0/9] Memory scrubbing from idle loop George Dunlap

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