From: Waiman Long <waiman.long@hp.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
linux-arch@vger.kernel.org, x86@kernel.org,
linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
xen-devel@lists.xenproject.org, kvm@vger.kernel.org,
Paolo Bonzini <paolo.bonzini@gmail.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Rik van Riel <riel@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
David Vrabel <david.vrabel@citrix.com>,
Oleg Nesterov <oleg@redhat.com>,
Daniel J Blueman <daniel@numascale.com>,
Scott J Norton <scott.norton@hp.com>,
Douglas Hatch <doug.hatch@hp.com>
Subject: Re: [PATCH v16 08/14] pvqspinlock: Implement simple paravirt support for the qspinlock
Date: Mon, 04 May 2015 13:15:52 -0400 [thread overview]
Message-ID: <5547A948.5050406@hp.com> (raw)
In-Reply-To: <20150504142017.GK23123@twins.programming.kicks-ass.net>
On 05/04/2015 10:20 AM, Peter Zijlstra wrote:
> I changed it to the below; I've not gotten around to compiling or even
> running it yet :-(
>
> The biggest change is the pv_hash/pv_unhash functions, which I've
> rewritten to hopefully be clearer (and also hopefully not wrecked them).
> I took out the cacheline sized structure which takes out that double
> loop and simplifies things. I've also added some comments which
> hopefully explain how/why we ended up with this exact scheme.
>
> I've also moved the __pv_queue_spin_unlock() function to the tail, such
> that we keep the 'wait'/'kick' order for both node and head.
>
> In any case, like I just wrote on the other email, I've stuck some
> things in my queue (up to and including patch 11) and if it all works
> out we can continue from there.
>
> ---
> Subject: pvqspinlock: Implement simple paravirt support for the qspinlock
> From: Waiman Long<Waiman.Long@hp.com>
> Date: Fri, 24 Apr 2015 14:56:37 -0400
>
> Provide a separate (second) version of the spin_lock_slowpath for
> paravirt along with a special unlock path.
>
> The second slowpath is generated by adding a few pv hooks to the
> normal slowpath, but where those will compile away for the native
> case, they expand into special wait/wake code for the pv version.
>
> The actual MCS queue can use extra storage in the mcs_nodes[] array to
> keep track of state and therefore uses directed wakeups.
>
> The head contender has no such storage directly visible to the
> unlocker. So the unlocker searches a hash table with open addressing
> using a simple binary Galois linear feedback shift register.
I am fine with the change as it makes it simpler. BTW, I just saw a
build error mail. That should be fixed easily with some minor edit.
Cheers,
Longman
next prev parent reply other threads:[~2015-05-04 17:15 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-24 18:56 [PATCH v16 00/14] qspinlock: a 4-byte queue spinlock with PV support Waiman Long
2015-04-24 18:56 ` [PATCH v16 01/14] qspinlock: A simple generic 4-byte queue spinlock Waiman Long
2015-04-24 18:56 ` [PATCH v16 02/14] qspinlock, x86: Enable x86-64 to use " Waiman Long
2015-04-24 18:56 ` [PATCH v16 03/14] qspinlock: Add pending bit Waiman Long
2015-04-24 18:56 ` [PATCH v16 04/14] qspinlock: Extract out code snippets for the next patch Waiman Long
2015-04-24 18:56 ` [PATCH v16 05/14] qspinlock: Optimize for smaller NR_CPUS Waiman Long
2015-04-24 18:56 ` [PATCH v16 06/14] qspinlock: Use a simple write to grab the lock Waiman Long
2015-04-24 18:56 ` [PATCH v16 07/14] qspinlock: Revert to test-and-set on hypervisors Waiman Long
2015-04-24 18:56 ` [PATCH v16 08/14] pvqspinlock: Implement simple paravirt support for the qspinlock Waiman Long
2015-05-04 14:20 ` Peter Zijlstra
2015-05-04 17:15 ` Waiman Long [this message]
2015-04-24 18:56 ` [PATCH v16 09/14] pvqspinlock, x86: Implement the paravirt qspinlock call patching Waiman Long
2015-04-24 18:56 ` [PATCH v16 10/14] pvqspinlock, x86: Enable PV qspinlock for KVM Waiman Long
2015-04-24 18:56 ` [PATCH v16 11/14] pvqspinlock, x86: Enable PV qspinlock for Xen Waiman Long
2015-04-24 18:56 ` [PATCH v16 12/14] pvqspinlock: Only kick CPU at unlock time Waiman Long
2015-04-24 18:56 ` [PATCH v16 13/14] pvqspinlock: Improve slowpath performance by avoiding cmpxchg Waiman Long
2015-04-29 18:11 ` Peter Zijlstra
2015-04-29 18:27 ` Linus Torvalds
2015-04-30 18:56 ` Waiman Long
2015-04-30 18:49 ` Waiman Long
2015-05-04 14:05 ` Peter Zijlstra
2015-05-04 17:18 ` Waiman Long
2015-04-24 18:56 ` [PATCH v16 14/14] pvqspinlock: Collect slowpath lock statistics Waiman Long
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=5547A948.5050406@hp.com \
--to=waiman.long@hp.com \
--cc=boris.ostrovsky@oracle.com \
--cc=daniel@numascale.com \
--cc=david.vrabel@citrix.com \
--cc=doug.hatch@hp.com \
--cc=hpa@zytor.com \
--cc=konrad.wilk@oracle.com \
--cc=kvm@vger.kernel.org \
--cc=linux-arch@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=oleg@redhat.com \
--cc=paolo.bonzini@gmail.com \
--cc=paulmck@linux.vnet.ibm.com \
--cc=peterz@infradead.org \
--cc=raghavendra.kt@linux.vnet.ibm.com \
--cc=riel@redhat.com \
--cc=scott.norton@hp.com \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
--cc=virtualization@lists.linux-foundation.org \
--cc=x86@kernel.org \
--cc=xen-devel@lists.xenproject.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).