From: Alexander Gordeev <agordeev@redhat.com>
To: Yinghai Lu <yinghai@kernel.org>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Bjorn Helgaas <bhelgaas@google.com>,
Suresh Siddha <suresh.b.siddha@intel.com>,
Jeff Garzik <jgarzik@pobox.com>,
Matthew Wilcox <willy@linux.intel.com>,
x86@kernel.org, linux-pci@vger.kernel.org,
linux-ide@vger.kernel.org
Subject: Re: [PATCH v2 -tip 1/5] x86, MSI: Support multiple MSIs in presense of IRQ remapping
Date: Tue, 4 Sep 2012 11:32:31 +0200 [thread overview]
Message-ID: <20120904093230.GA17873@dhcp-26-207.brq.redhat.com> (raw)
In-Reply-To: <CAE9FiQUuAPy884Ytu5PrFkcoQ5tT_DPxyYDk1D1jKbo+G577Mw@mail.gmail.com>
On Mon, Sep 03, 2012 at 11:53:39AM -0700, Yinghai Lu wrote:
> On Mon, Sep 3, 2012 at 2:17 AM, Alexander Gordeev <agordeev@redhat.com> wrote:
> You may update create_irq_nr to be __create_irq_nr, and it could take
> extra count.
>
> and later have create_irq_nr to be __create_irq_nr(,1,)
> and create_irqs to be __create_irq_nr(,count,)
> ....
Indeed. Will do.
> BTW, in short, how much performance benefits for adding 500 lines code?
Unfortunatelly, I do not have a short answer here. There are three types
of performance this series deals with - I'll try to summarize:
- devices - 3 SATA HDDs generate roughly one interrupt every 273 us while
it get handled in less than 5 us. So there is/could be no increase here;
- the hardware context interrupt handler - its performance dropped 2.5 times
(little bit more in fact) at the expense of increase of 1.3 times in
overall interrupt handling time (hardware context + threaded context);
- overall system performance - I *assume* it should increase, because:
(a) AHCI interrupt handlers keep local interrupts disabled 2.5 times less
(b) separate AHCI IRQs become subjects of IRQ balancing
(c) threaded handlers are per-device, per-CPU (well, up to irqbalanced)
and executed with local interrupts enabled;
--
Regards,
Alexander Gordeev
agordeev@redhat.com
next prev parent reply other threads:[~2012-09-04 9:32 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-03 9:16 [PATCH v2 -tip 0/5] x86, MSI, AHCI: Support multiple MSIs Alexander Gordeev
2012-09-03 9:17 ` [PATCH v2 -tip 1/5] x86, MSI: Support multiple MSIs in presense of IRQ remapping Alexander Gordeev
2012-09-03 18:53 ` Yinghai Lu
2012-09-04 9:32 ` Alexander Gordeev [this message]
2012-09-03 9:18 ` [PATCH v2 -tip 2/5] x86, MSI: Allocate as many multiple IRQs as requested Alexander Gordeev
2012-09-03 9:19 ` [PATCH v2 -tip 3/5] x86, MSI: Minor readability fixes Alexander Gordeev
2012-09-03 9:19 ` [PATCH v2 -tip 4/5] PCI, MSI: Enable multiple MSIs with pci_enable_msi_block_auto() Alexander Gordeev
2012-09-07 20:53 ` Bjorn Helgaas
2012-09-03 9:20 ` [PATCH v2 -tip 5/5] AHCI: Support multiple MSIs Alexander Gordeev
2012-09-27 4:59 ` Jeff Garzik
2012-09-26 12:38 ` [PATCH v2 -tip 0/5] x86, MSI, " Alexander Gordeev
2012-09-27 4:03 ` Ingo Molnar
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