LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Joerg Roedel <joro@8bytes.org>
To: Dmitry Osipenko <digetx@gmail.com>
Cc: Robin Murphy <robin.murphy@arm.com>,
	Thierry Reding <thierry.reding@gmail.com>,
	linux-tegra@vger.kernel.org, iommu@lists.linux-foundation.org,
	linux-kernel@vger.kernel.org,
	Jonathan Hunter <jonathanh@nvidia.com>
Subject: Re: [PATCH v1 4/4] iommu/tegra: gart: Optimize map/unmap
Date: Mon, 7 May 2018 10:04:20 +0200	[thread overview]
Message-ID: <20180507080420.GB18595@8bytes.org> (raw)
In-Reply-To: <6827bda3-1aa2-da60-a749-8e2dd2e595f3@gmail.com>

On Mon, May 07, 2018 at 12:19:01AM +0300, Dmitry Osipenko wrote:
> Probably the best variant would be to give an explicit control over syncing to a
> user of the IOMMU API, like for example device driver may perform multiple
> mappings / unmappings and then sync/flush in the end. I'm not sure that it's
> really worth the hassle to shuffle the API right now, maybe we can implement it
> later if needed. Joerg, do you have objections to a 'compound page' approach?

Have you measured the performance difference on both variants? The
compound-page approach only works for cases when the physical memory you
map contiguous and correctly aligned.

If it is really needed I would prefer a separate iotlb_sync_map()
call-back that is just NULL when not needed. This way all users that
don't need it only get a minimal penalty in the mapping path and you
don't have any requirements on the physical memory you map to get good
performance.


	Joerg

  reply	other threads:[~2018-05-07  8:04 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-09 20:07 [PATCH v1 0/4] Tegra GART fixes and improvements Dmitry Osipenko
2018-04-09 20:07 ` [PATCH v1 1/4] iommu/tegra: gart: Add debugging facility Dmitry Osipenko
2018-04-27  9:46   ` Thierry Reding
2018-04-09 20:07 ` [PATCH v1 2/4] iommu/tegra: gart: Fix gart_iommu_unmap() Dmitry Osipenko
2018-04-27  9:43   ` Thierry Reding
2018-04-09 20:07 ` [PATCH v1 3/4] iommu/tegra: gart: Constify number of GART pages Dmitry Osipenko
2018-04-27  9:49   ` Thierry Reding
2018-04-09 20:07 ` [PATCH v1 4/4] iommu/tegra: gart: Optimize map/unmap Dmitry Osipenko
2018-04-27 10:02   ` Thierry Reding
2018-04-27 12:01     ` Dmitry Osipenko
2018-04-27 12:36     ` Robin Murphy
2018-05-06 21:19       ` Dmitry Osipenko
2018-05-07  8:04         ` Joerg Roedel [this message]
2018-05-07 15:51           ` Dmitry Osipenko
2018-05-07 17:38             ` Dmitry Osipenko
2018-05-07  7:59     ` Joerg Roedel
2018-05-07 15:46       ` Dmitry Osipenko
2018-05-03 12:52 ` [PATCH v1 0/4] Tegra GART fixes and improvements Joerg Roedel

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20180507080420.GB18595@8bytes.org \
    --to=joro@8bytes.org \
    --cc=digetx@gmail.com \
    --cc=iommu@lists.linux-foundation.org \
    --cc=jonathanh@nvidia.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-tegra@vger.kernel.org \
    --cc=robin.murphy@arm.com \
    --cc=thierry.reding@gmail.com \
    --subject='Re: [PATCH v1 4/4] iommu/tegra: gart: Optimize map/unmap' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).