From: Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
To: Thierry Reding <thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Dmitry Osipenko <digetx-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
Jonathan Hunter
<jonathanh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
Subject: Re: [PATCH v1 4/4] iommu/tegra: gart: Optimize map/unmap
Date: Mon, 7 May 2018 09:59:21 +0200 [thread overview]
Message-ID: <20180507075920.GA18595@8bytes.org> (raw)
In-Reply-To: <20180427100202.GO30388@ulmo>
On Fri, Apr 27, 2018 at 12:02:02PM +0200, Thierry Reding wrote:
> Joerg, I've gone over the git log and header files and I see no mention
> of why the TLB flush interface isn't used for mapping. Do you recall any
> special reasons why the same shouldn't be applied for mapping? Would you
> accept any patches doing this?
Yeah, the reason was that we assumed that only emulated IOMMUs ever need
flushing in the mapping path, and there is no reason to optimize for
that. Especially when a call to iotlb_sync() in the mapping path would
hurt most other users.
Does the tegra-gart actually need it too?
Joerg
WARNING: multiple messages have this Message-ID (diff)
From: Joerg Roedel <joro@8bytes.org>
To: Thierry Reding <thierry.reding@gmail.com>
Cc: Dmitry Osipenko <digetx@gmail.com>,
Jonathan Hunter <jonathanh@nvidia.com>,
iommu@lists.linux-foundation.org, linux-tegra@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1 4/4] iommu/tegra: gart: Optimize map/unmap
Date: Mon, 7 May 2018 09:59:21 +0200 [thread overview]
Message-ID: <20180507075920.GA18595@8bytes.org> (raw)
In-Reply-To: <20180427100202.GO30388@ulmo>
On Fri, Apr 27, 2018 at 12:02:02PM +0200, Thierry Reding wrote:
> Joerg, I've gone over the git log and header files and I see no mention
> of why the TLB flush interface isn't used for mapping. Do you recall any
> special reasons why the same shouldn't be applied for mapping? Would you
> accept any patches doing this?
Yeah, the reason was that we assumed that only emulated IOMMUs ever need
flushing in the mapping path, and there is no reason to optimize for
that. Especially when a call to iotlb_sync() in the mapping path would
hurt most other users.
Does the tegra-gart actually need it too?
Joerg
next prev parent reply other threads:[~2018-05-07 7:59 UTC|newest]
Thread overview: 34+ 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 ` Dmitry Osipenko
[not found] ` <cover.1523304324.git.digetx-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2018-04-09 20:07 ` [PATCH v1 1/4] iommu/tegra: gart: Add debugging facility Dmitry Osipenko
2018-04-09 20:07 ` 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
2018-04-09 20:07 ` Dmitry Osipenko
[not found] ` <dd25a9ff7bad7c92b345c0c0ce2bf235c4c3b6e8.1523304324.git.digetx-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2018-04-27 9:43 ` Thierry Reding
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
2018-04-09 20:07 ` Dmitry Osipenko
[not found] ` <954659be6760130f6ffd5e733db2ad58cbb8e6e4.1523304324.git.digetx-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2018-04-27 9:49 ` Thierry Reding
2018-04-27 9:49 ` Thierry Reding
2018-04-09 20:07 ` [PATCH v1 4/4] iommu/tegra: gart: Optimize map/unmap Dmitry Osipenko
2018-04-09 20:07 ` Dmitry Osipenko
[not found] ` <f21a7b6a8f141b87f75687904a76f3728ea639a8.1523304324.git.digetx-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2018-04-27 10:02 ` Thierry Reding
2018-04-27 10:02 ` Thierry Reding
2018-04-27 12:01 ` Dmitry Osipenko
2018-04-27 12:36 ` Robin Murphy
2018-04-27 12:36 ` Robin Murphy
[not found] ` <716edf58-38a7-21e5-1668-b866bf392e34-5wv7dgnIgG8@public.gmane.org>
2018-05-06 21:19 ` Dmitry Osipenko
2018-05-06 21:19 ` Dmitry Osipenko
[not found] ` <6827bda3-1aa2-da60-a749-8e2dd2e595f3-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2018-05-07 8:04 ` Joerg Roedel
2018-05-07 8:04 ` Joerg Roedel
[not found] ` <20180507080420.GB18595-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2018-05-07 15:51 ` Dmitry Osipenko
2018-05-07 15:51 ` Dmitry Osipenko
[not found] ` <a6e26d17-97ac-d02e-7bf4-f009af1a25dc-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2018-05-07 17:38 ` Dmitry Osipenko
2018-05-07 17:38 ` Dmitry Osipenko
2018-05-07 7:59 ` Joerg Roedel [this message]
2018-05-07 7:59 ` Joerg Roedel
[not found] ` <20180507075920.GA18595-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2018-05-07 15:46 ` Dmitry Osipenko
2018-05-07 15:46 ` Dmitry Osipenko
2018-05-03 12:52 ` [PATCH v1 0/4] Tegra GART fixes and improvements Joerg Roedel
2018-05-03 12:52 ` Joerg Roedel
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