linux-kernel - Re: AMD-Vi: Decrease time of enabling lazy IO/TLB flushing

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Message-ID: <20180720123450.GD18541@8bytes.org>
Date:   Fri, 20 Jul 2018 14:34:50 +0200
From:   Jörg Rödel <joro@...tes.org>
To:     Paul Menzel <pmenzel+linux-iommu@...gen.mpg.de>
Cc:     iommu@...ts.linux-foundation.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: AMD-Vi: Decrease time of enabling lazy IO/TLB flushing

On Tue, Jul 17, 2018 at 06:07:07PM +0200, Paul Menzel wrote:
> On a MSI B350M MORTAR with AMD Ryzen 3 2200g (Raven) with Linux 4.18-rc5+
> and Debian Sid/unstable `pci_iommu_init` takes 40 ms according to
> `initcall_debug`.

40ms is a lot indeed, but IOMMU initialization is also a complex process
which includes scanning ACPI tables, allocating memory, flushing
hardware caches (which probably accounts for a fair amount of the time
needed).

Would be good if someone can come up with patches to improve the
situation here, as I don't know when I will find the time to look into
that.

Thanks,

	Joerg