linux-kernel - Re: [PATCH] iommu/vt-d: Introduce a rb

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Message-ID: <ZRFA3uj1-QjlXpGx@8bytes.org>
Date:   Mon, 25 Sep 2023 10:12:14 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     Huang Jiaqing <jiaqing.huang@...el.com>
Cc:     kvm@...r.kernel.org, iommu@...ts.linux.dev,
        linux-kernel@...r.kernel.org, will@...nel.org,
        robin.murphy@....com, kevin.tian@...el.com,
        baolu.lu@...ux.intel.com, jacob.jun.pan@...ux.intel.com,
        yi.l.liu@...el.com, yi.y.sun@...el.com
Subject: Re: [PATCH] iommu/vt-d: Introduce a rb_tree for looking up device

On Mon, Aug 21, 2023 at 12:16:59AM -0700, Huang Jiaqing wrote:
> The existing IO page fault handler locates the PCI device by calling
> pci_get_domain_bus_and_slot(), which searches the list of all PCI
> devices until the desired PCI device is found. This is inefficient
> because the algorithm efficiency of searching a list is O(n). In the
> critical path of handling an IO page fault, this can cause a significant
> performance bottleneck.

Can you elaborate a little more on the 'significant performance
bottleneck' part? Where do you see this as a problem?

Regards,

	Joerg