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Re: [4.2, Regression] Queued spinlocks cause major XFS performance regression

From Linus Torvalds <torvalds@linux-foundation.org>
Newsgroups linux.kernel
Subject Re: [4.2, Regression] Queued spinlocks cause major XFS performance regression
Date 2015-09-07 22:50 +0200
Message-ID <q6bwt-863-15@gated-at.bofh.it> (permalink)
References (4 earlier) <q50MO-5FD-9@gated-at.bofh.it> <q50Wu-5QK-11@gated-at.bofh.it> <q516c-61Z-29@gated-at.bofh.it> <q5Sat-5Rx-7@gated-at.bofh.it> <q5Yzg-6qO-1@gated-at.bofh.it>
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On Sun, Sep 6, 2015 at 11:57 PM, Peter Zijlstra <peterz@infradead.org> wrote:
>
> Just to continue the argument for arguments sake, the function is named
> 'virt' (not paravirt) and tests the HYPERVISOR CPUID bit. How is that
> not appropriately named?

Well, I think right now one issue is that you can't avoid it, even
when you want pure "raw hardware" spinlocks.

I really think it should at the very least be inside CONFIG_PARAVIRT.
Because it *is* about helping the hypervisor, so really is about
paravirtualization.

So naming is misleading, I think, and the config option situation is
not great. If you act differently under virtualization than you do on
raw hardware, what would you call that? I'd call it "paravirt".

             Linus
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Thread

[4.2, Regression] Queued spinlocks cause major XFS performance  regression Dave Chinner <david@fromorbit.com> - 2015-09-04 07:50 +0200
  Re: [4.2, Regression] Queued spinlocks cause major XFS performance regression Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-04 08:40 +0200
    Re: [4.2, Regression] Queued spinlocks cause major XFS performance  regression Dave Chinner <david@fromorbit.com> - 2015-09-04 09:20 +0200
      Re: [4.2, Regression] Queued spinlocks cause major XFS performance  regression Juergen Gross <jgross@suse.com> - 2015-09-04 09:40 +0200
      Re: [4.2, Regression] Queued spinlocks cause major XFS performance  regression Peter Zijlstra <peterz@infradead.org> - 2015-09-04 10:00 +0200
      Re: [4.2, Regression] Queued spinlocks cause major XFS performance  regression Dave Chinner <david@fromorbit.com> - 2015-09-04 10:40 +0200
        Re: [4.2, Regression] Queued spinlocks cause major XFS performance regression Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-04 17:10 +0200
          Re: [4.2, Regression] Queued spinlocks cause major XFS performance  regression Peter Zijlstra <peterz@infradead.org> - 2015-09-04 17:20 +0200
            Re: [4.2, Regression] Queued spinlocks cause major XFS performance  regression Peter Zijlstra <peterz@infradead.org> - 2015-09-04 17:30 +0200
              Re: [4.2, Regression] Queued spinlocks cause major XFS performance  regression Dave Chinner <david@fromorbit.com> - 2015-09-07 01:40 +0200
              Re: [4.2, Regression] Queued spinlocks cause major XFS performance  regression Davidlohr Bueso <dave@stgolabs.net> - 2015-09-07 02:10 +0200
                Re: [4.2, Regression] Queued spinlocks cause major XFS performance  regression Peter Zijlstra <peterz@infradead.org> - 2015-09-07 09:00 +0200
                Re: [4.2, Regression] Queued spinlocks cause major XFS performance regression Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-07 22:50 +0200
                Re: [4.2, Regression] Queued spinlocks cause major XFS performance  regression Davidlohr Bueso <dave@stgolabs.net> - 2015-09-08 08:40 +0200
                Re: [4.2, Regression] Queued spinlocks cause major XFS performance  regression Peter Zijlstra <peterz@infradead.org> - 2015-09-08 12:10 +0200
                Re: [4.2, Regression] Queued spinlocks cause major XFS performance regression Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-08 19:50 +0200
              [tip:locking/core] locking/qspinlock/x86:   Fix performance regression under unaccelerated VMs tip-bot for Peter Zijlstra <tipbot@zytor.com> - 2015-09-13 13:00 +0200
            Re: [4.2, Regression] Queued spinlocks cause major XFS performance regression Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-04 17:30 +0200
              Re: [4.2, Regression] Queued spinlocks cause major XFS performance  regression Peter Zijlstra <peterz@infradead.org> - 2015-09-04 17:40 +0200
                Re: [4.2, Regression] Queued spinlocks cause major XFS performance  regression Peter Zijlstra <peterz@infradead.org> - 2015-09-04 18:00 +0200
                Re: [4.2, Regression] Queued spinlocks cause major XFS performance  regression Waiman Long <waiman.long@hpe.com> - 2015-09-10 04:20 +0200
                Re: [4.2, Regression] Queued spinlocks cause major XFS performance regression Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-04 18:00 +0200
                Re: [4.2, Regression] Queued spinlocks cause major XFS performance  regression Peter Zijlstra <peterz@infradead.org> - 2015-09-05 19:50 +0200
    Re: [4.2, Regression] Queued spinlocks cause major XFS performance  regression Peter Zijlstra <peterz@infradead.org> - 2015-09-04 09:40 +0200
      Re: [4.2, Regression] Queued spinlocks cause major XFS performance  regression Peter Zijlstra <peterz@infradead.org> - 2015-09-04 13:40 +0200
        Re: [4.2, Regression] Queued spinlocks cause major XFS performance  regression Dave Chinner <david@fromorbit.com> - 2015-09-05 00:10 +0200
        Re: [4.2, Regression] Queued spinlocks cause major XFS performance  regression Dave Chinner <david@fromorbit.com> - 2015-09-07 01:50 +0200
          Re: [4.2, Regression] Queued spinlocks cause major XFS performance  regression Waiman Long <waiman.long@hpe.com> - 2015-09-10 04:10 +0200
  Re: [4.2, Regression] Queued spinlocks cause major XFS performance  regression Waiman Long <waiman.long@hpe.com> - 2015-09-10 04:20 +0200

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