From: "Patel, Nirmal" <nirmal.patel@linux.intel.com>
To: Xinghui Li <korantwork@gmail.com>,
Jonathan Derrick <jonathan.derrick@linux.dev>
Cc: Keith Busch <kbusch@kernel.org>,
lpieralisi@kernel.org, linux-pci@vger.kernel.org,
linux-kernel@vger.kernel.org, Xinghui Li <korantli@tencent.com>
Subject: Re: [PATCH] PCI: vmd: Do not disable MSI-X remapping in VMD 28C0 controller
Date: Mon, 6 Feb 2023 11:11:36 -0700 [thread overview]
Message-ID: <9e6cfda1-4309-d1bb-a0cf-404a7fe7d3aa@linux.intel.com> (raw)
In-Reply-To: <CAEm4hYWeZFrYxSvAcBJ8iw=t507vZMqfBwiQXFSJd2Hcyfw7fA@mail.gmail.com>
On 2/6/2023 5:45 AM, Xinghui Li wrote:
> Friendly ping~
>
> Xinghui Li <korantwork@gmail.com> 于2023年1月10日周二 20:28写道：
>> Jonathan Derrick <jonathan.derrick@linux.dev> 于2023年1月10日周二 05:00写道：
>>> As the bypass mode seems to affect performance greatly depending on the specific configuration,
>>> it may make sense to use a moduleparam to control it
>>>
>> We found that each pcie port can mount four drives. If we only test 2
>> or 1 dirve of one pcie port,
>> the performance of the drive performance will be normal. Also, we
>> observed the interruptions in different modes.
>> bypass:
>> .....
>> 2022-12-28-11-39-14: 1224 181665 IR-PCI-MSI 201850948-edge nvme0q68
>> 2022-12-28-11-39-14: 1179 180115 IR-PCI-MSI 201850945-edge nvme0q65
>> 2022-12-28-11-39-14: RES 26743 Rescheduling interrupts
>> 2022-12-28-11-39-17: irqtop - IRQ : 3029, TOTAL : 2100315228, CPU :
>> 192, ACTIVE CPU : 192
>> disable:
>> ......
>> 2022-12-28-12-05-56: 1714 169797 IR-PCI-MSI 14155850-edge nvme1q74
>> 2022-12-28-12-05-56: 1701 168753 IR-PCI-MSI 14155849-edge nvme1q73
>> 2022-12-28-12-05-56: LOC 163697 Local timer interrupts
>> 2022-12-28-12-05-56: TLB 5465 TLB shootdowns
>> 2022-12-28-12-06-00: irqtop - IRQ : 3029, TOTAL : 2179022106, CPU :
>> 192, ACTIVE CPU : 192
>> remapping:
>> 022-12-28-11-25-38: 283 325568 IR-PCI-MSI 24651790-edge vmd3
>> 2022-12-28-11-25-38: 140 267899 IR-PCI-MSI 13117447-edge vmd1
>> 2022-12-28-11-25-38: 183 265978 IR-PCI-MSI 13117490-edge vmd1
>> ......
>> 2022-12-28-11-25-42: irqtop - IRQ : 2109, TOTAL : 2377172002, CPU :
>> 192, ACTIVE CPU : 192
>>
>> From the result it is not difficult to find, in remapping mode the
>> interruptions come from vmd.
>> While in other modes, interrupts come from nvme devices. Besides, we
>> found the port mounting
>> 4 dirves total interruptions is much fewer than the port mounting 2 or 1 drive.
>> NVME 8 and 9 mount in one port, other port mount 4 dirves.
>>
>> 2022-12-28-11-39-14: 2582 494635 IR-PCI-MSI 470810698-edge nvme9q74
>> 2022-12-28-11-39-14: 2579 489972 IR-PCI-MSI 470810697-edge nvme9q73
>> 2022-12-28-11-39-14: 2573 480024 IR-PCI-MSI 470810695-edge nvme9q71
>> 2022-12-28-11-39-14: 2544 312967 IR-PCI-MSI 470286401-edge nvme8q65
>> 2022-12-28-11-39-14: 2556 312229 IR-PCI-MSI 470286405-edge nvme8q69
>> 2022-12-28-11-39-14: 2547 310013 IR-PCI-MSI 470286402-edge nvme8q66
>> 2022-12-28-11-39-14: 2550 308993 IR-PCI-MSI 470286403-edge nvme8q67
>> 2022-12-28-11-39-14: 2559 308794 IR-PCI-MSI 470286406-edge nvme8q70
>> ......
>> 2022-12-28-11-39-14: 1296 185773 IR-PCI-MSI 202375243-edge nvme1q75
>> 2022-12-28-11-39-14: 1209 185646 IR-PCI-MSI 201850947-edge nvme0q67
>> 2022-12-28-11-39-14: 1831 184151 IR-PCI-MSI 203423828-edge nvme3q84
>> 2022-12-28-11-39-14: 1254 182313 IR-PCI-MSI 201850950-edge nvme0q70
>> 2022-12-28-11-39-14: 1224 181665 IR-PCI-MSI 201850948-edge nvme0q68
>> 2022-12-28-11-39-14: 1179 180115 IR-PCI-MSI 201850945-edge nvme0q65
>>> I'd vote for it being in VMD mode (non-bypass) by default.
>> I speculate that the vmd controller equalizes the interrupt load and
>> acts like a buffer,
>> which improves the performance of nvme. I am not sure about my
>> analysis. So, I'd like
>> to discuss it with the community.
I like the idea of module parameter to allow switching between the modes
but keep MSI remapping enabled (non-bypass) by default.
next prev parent reply other threads:[~2023-02-06 18:12 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-22 7:26 [PATCH] PCI: vmd: Do not disable MSI-X remapping in VMD 28C0 controller korantwork
2022-12-22 9:15 ` Jonathan Derrick
2022-12-22 21:56 ` Keith Busch
2022-12-23 8:02 ` Xinghui Li
2022-12-27 22:32 ` Jonathan Derrick
2022-12-28 2:19 ` Xinghui Li
2023-01-09 21:00 ` Jonathan Derrick
2023-01-10 12:28 ` Xinghui Li
2023-02-06 12:45 ` Xinghui Li
2023-02-06 18:11 ` Patel, Nirmal [this message]
2023-02-06 18:28 ` Keith Busch
2023-02-07 3:18 ` Xinghui Li
2023-02-07 20:32 ` Patel, Nirmal
2023-02-09 12:05 ` Xinghui Li
2023-02-09 23:05 ` Keith Busch
2023-02-09 23:57 ` Patel, Nirmal
2023-02-10 0:47 ` Keith Busch
2022-12-23 7:53 ` Xinghui Li
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