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From: tedheadster <tedheadster-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>
Cc: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
	x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org,
	konrad.wilk-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org
Subject: Re: [PATCH] x86: enable swiotlb for > 4GiG ram on 32-bit kernels
Date: Tue, 16 Oct 2018 09:11:09 -0400	[thread overview]
Message-ID: <CAP8WD_Zj5aMcTCVtV-hot3zLNfNuMzHyeogm0Lqb=+XZ1LdkKw@mail.gmail.com> (raw)
In-Reply-To: <20181014075208.2715-1-hch-jcswGhMUV9g@public.gmane.org>

On Sun, Oct 14, 2018 at 3:52 AM Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org> wrote:
>
> We already build the swiotlb code for 32b-t kernels with PAE support,
> but the code to actually use swiotlb has only been enabled for 64-bit
> kernel for an unknown reason.
>
> Before Linux 4.18 we papers over this fact because the networking code,
> the scsi layer and some random block drivers implenented their own
> bounce buffering scheme.
>
> Fixes: 21e07dba ("scsi: reduce use of block bounce buffers")
> Fixes: ab74cfeb ("net: remove the PCI_DMA_BUS_IS_PHYS check in illegal_highdma")
> Reported-by: tedheadster <tedheadster-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> Tested-by: tedheadster <tedheadster-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> ---
>

Christoph,
  this fix has causes performance to decrease dramatically. Kernel
builds that used to take 10-15 minutes are now taking 45-60 minutes on
the same machine.

- Matthew Whitehead

  parent reply	other threads:[~2018-10-16 13:11 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-14  7:52 [PATCH] x86: enable swiotlb for > 4GiG ram on 32-bit kernels Christoph Hellwig
2018-10-14  7:52 ` Christoph Hellwig
2018-10-14  8:13 ` Thomas Gleixner
2018-10-14  8:13   ` Thomas Gleixner
2018-10-14  8:14   ` Christoph Hellwig
2018-10-14  8:14     ` Christoph Hellwig
2018-10-14  8:57     ` Thomas Gleixner
2018-10-14  8:57       ` Thomas Gleixner
2018-10-14  9:04       ` Ingo Molnar
2018-10-14  9:04         ` Ingo Molnar
2018-10-14 12:49         ` tedheadster
2018-10-14  9:18 ` [tip:x86/urgent] x86/swiotlb: Enable " tip-bot for Christoph Hellwig
2018-10-15  9:09 ` tip-bot for Christoph Hellwig
2018-10-15 18:52 ` [PATCH] x86: enable " Konrad Rzeszutek Wilk
2018-10-15 18:52   ` Konrad Rzeszutek Wilk
     [not found] ` <20181014075208.2715-1-hch-jcswGhMUV9g@public.gmane.org>
2018-10-16 13:11   ` tedheadster [this message]
     [not found]     ` <CAP8WD_Zj5aMcTCVtV-hot3zLNfNuMzHyeogm0Lqb=+XZ1LdkKw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2018-10-17 10:16       ` Thomas Gleixner
2018-10-17 16:33       ` Christoph Hellwig
     [not found]         ` <20181017163351.GA23719-jcswGhMUV9g@public.gmane.org>
2018-10-17 17:41           ` tedheadster
     [not found]             ` <CAP8WD_boL-DxEXxa-ci382Ff8yTdMS9T+sy2Y0-LEX-WPc8L_g-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2018-10-18 12:51               ` Christoph Hellwig
     [not found]                 ` <20181018125116.GA24676-jcswGhMUV9g@public.gmane.org>
2018-10-19  1:00                   ` tedheadster
     [not found]                     ` <CAP8WD_Z2XvLsqimSnODwr5gj6GRuzh4SMKN56n6Y0JzufG=E8A-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2018-10-19  5:51                       ` Ingo Molnar
2018-10-18  6:12       ` Ingo Molnar
2018-10-19  5:54 ` [tip:x86/urgent] x86/swiotlb: Enable swiotlb for > 4GiG RAM " tip-bot for Christoph Hellwig

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