From: Christoph Hellwig <hch@infradead.org>
To: Jon Derrick <jonathan.derrick@intel.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Keith Busch <kbusch@kernel.org>,
Bjorn Helgaas <helgaas@kernel.org>,
linux-pci@vger.kernel.org
Subject: Re: [PATCH 0/3] PCI: vmd: Reducing tail latency by affining to the storage stack
Date: Thu, 7 Nov 2019 01:39:52 -0800 [thread overview]
Message-ID: <20191107093952.GA13826@infradead.org> (raw)
In-Reply-To: <1573040408-3831-1-git-send-email-jonathan.derrick@intel.com>
On Wed, Nov 06, 2019 at 04:40:05AM -0700, Jon Derrick wrote:
> This patchset optimizes VMD performance through the storage stack by locating
> commonly-affined NVMe interrupts on the same VMD interrupt handler lists.
>
> The current strategy of round-robin assignment to VMD IRQ lists can be
> suboptimal when vectors with different affinities are assigned to the same VMD
> IRQ list. VMD is an NVMe storage domain and this set aligns the vector
> allocation and affinity strategy with that of the NVMe driver. This invokes the
> kernel to do the right thing when affining NVMe submission cpus to NVMe
> completion vectors as serviced through the VMD interrupt handler lists.
>
> This set greatly reduced tail latency when testing 8 threads of random 4k reads
> against two drives at queue depth=128. After pinning the tasks to reduce test
> variability, the tests also showed a moderate tail latency reduction. A
> one-drive configuration also shows improvements due to the alignment of VMD IRQ
> list affinities with NVMe affinities.
How does this compare to simplify disabling VMD?
next prev parent reply other threads:[~2019-11-07 9:39 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-06 11:40 [PATCH 0/3] PCI: vmd: Reducing tail latency by affining to the storage stack Jon Derrick
2019-11-06 11:40 ` [PATCH 1/3] PCI: vmd: Reduce VMD vectors using NVMe calculation Jon Derrick
2019-11-06 18:02 ` Keith Busch
2019-11-06 19:51 ` Derrick, Jonathan
2019-11-06 11:40 ` [PATCH 2/3] PCI: vmd: Align IRQ lists with child device vectors Jon Derrick
2019-11-06 18:06 ` Keith Busch
2019-11-06 20:14 ` Derrick, Jonathan
2019-11-06 11:40 ` [PATCH 3/3] PCI: vmd: Use managed irq affinities Jon Derrick
2019-11-06 18:10 ` Keith Busch
2019-11-06 20:14 ` Derrick, Jonathan
2019-11-06 20:27 ` Keith Busch
2019-11-06 20:33 ` Derrick, Jonathan
2019-11-18 10:49 ` Lorenzo Pieralisi
2019-11-18 16:43 ` Derrick, Jonathan
2019-11-07 9:39 ` Christoph Hellwig [this message]
2019-11-07 14:12 ` [PATCH 0/3] PCI: vmd: Reducing tail latency by affining to the storage stack Derrick, Jonathan
2019-11-07 15:37 ` hch
2019-11-07 15:40 ` Derrick, Jonathan
2019-11-07 15:42 ` hch
2019-11-07 15:47 ` Derrick, Jonathan
2019-11-11 17:03 ` hch
2022-12-23 2:33 ` Kai-Heng Feng
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