From: KyongHo Cho <pullip.cho@samsung.com>
To: Ohad Ben-Cohen <ohad@wizery.com>
Cc: Arnd Bergmann <arnd@arndb.de>,
Joerg Roedel <Joerg.Roedel@amd.com>,
Hiroshi DOYU <Hiroshi.DOYU@nokia.com>,
linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
David Brown <davidb@codeaurora.org>,
linux-omap@vger.kernel.org, David Woodhouse <dwmw2@infradead.org>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [RFC 7/7] iommu/core: split mapping to page sizes as supported by the hardware
Date: Thu, 8 Sep 2011 21:51:57 +0900 [thread overview]
Message-ID: <CAHQjnONUvBtKSMxiDf5Mk+DLqfrTr09Us11rWoaR1mVZeiAmnA@mail.gmail.com> (raw)
In-Reply-To: <CAK=WgbbFhmiC=PJfmyPOhbHGtiPFOcmqBx7nSpkuDX36hPYgbA@mail.gmail.com>
Hi Ohad,
On Wed, Sep 7, 2011 at 6:16 PM, Ohad Ben-Cohen <ohad@wizery.com> wrote:
> Hmm this sounds a bit like a red herring to me; optimization of the
:) I agree. sorry.
> map function is not the main subject here. Especially not when we're
> discussing mapping of large physically contiguous memory regions which
> do not happen too often.
>
I've got your point but I thought that it is really needed.
> Another advantage for migrating s5p_iommu_map() over to the subject
> patch, is that s5p_iommu_map() doesn't support super sections yet. To
> support it, you'd need to add more code (duplicate another while
> loop). But if you migrated to the subject patch, then you would only
> need to flip the 16MB bit when you advertise page size capabilities
> and then that's it; you're done.
I did not implement that.
16MB page is less practical in Linux because Linux kernel is unable
to allocated larger physically contiguous memory than 4MB by default.
But I also think that it is needed to support 16MB mapping for IO
virtualization someday
and it is just trivial job.
And you pointed correctly that s5p_iommu_map() has duplicate similar codes.
Actually, I think your idea is good and does not cause performance degradation.
But I wondered if it is really useful.
>
> The caller of iommu_map() doesn't say anything about alignments. It
> just gives it a memory region to map, and expect things to just work.
>
The caller of iommu_map() gives gfp_order that is the size of the physical
memory to map.
I thought that it also means alignment of the physical memory.
Isn't it?
Regards,
KyongHo
WARNING: multiple messages have this Message-ID (diff)
From: pullip.cho@samsung.com (KyongHo Cho)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC 7/7] iommu/core: split mapping to page sizes as supported by the hardware
Date: Thu, 8 Sep 2011 21:51:57 +0900 [thread overview]
Message-ID: <CAHQjnONUvBtKSMxiDf5Mk+DLqfrTr09Us11rWoaR1mVZeiAmnA@mail.gmail.com> (raw)
In-Reply-To: <CAK=WgbbFhmiC=PJfmyPOhbHGtiPFOcmqBx7nSpkuDX36hPYgbA@mail.gmail.com>
Hi Ohad,
On Wed, Sep 7, 2011 at 6:16 PM, Ohad Ben-Cohen <ohad@wizery.com> wrote:
> Hmm this sounds a bit like a red herring to me; optimization of the
:) I agree. sorry.
> map function is not the main subject here. Especially not when we're
> discussing mapping of large physically contiguous memory regions which
> do not happen too often.
>
I've got your point but I thought that it is really needed.
> Another advantage for migrating s5p_iommu_map() over to the subject
> patch, is that s5p_iommu_map() doesn't support super sections yet. To
> support it, you'd need to add more code (duplicate another while
> loop). But if you migrated to the subject patch, then you would only
> need to flip the 16MB bit when you advertise page size capabilities
> and then that's it; you're done.
I did not implement that.
16MB page is less practical in Linux because Linux kernel is unable
to allocated larger physically contiguous memory than 4MB by default.
But I also think that it is needed to support 16MB mapping for IO
virtualization someday
and it is just trivial job.
And you pointed correctly that s5p_iommu_map() has duplicate similar codes.
Actually, I think your idea is good and does not cause performance degradation.
But I wondered if it is really useful.
>
> The caller of iommu_map() doesn't say anything about alignments. It
> just gives it a memory region to map, and expect things to just work.
>
The caller of iommu_map() gives gfp_order that is the size of the physical
memory to map.
I thought that it also means alignment of the physical memory.
Isn't it?
Regards,
KyongHo
next prev parent reply other threads:[~2011-09-08 12:52 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-02 17:32 [PATCH/RFC 0/7] iommu: fixes & extensions Ohad Ben-Cohen
2011-09-02 17:32 ` Ohad Ben-Cohen
2011-09-02 17:32 ` Ohad Ben-Cohen
2011-09-02 17:32 ` [PATCH 1/7] iommu/omap-iovmm: support non page-aligned buffers in iommu_vmap Ohad Ben-Cohen
2011-09-02 17:32 ` Ohad Ben-Cohen
2011-09-02 17:32 ` Ohad Ben-Cohen
2011-09-02 17:32 ` [PATCH 2/7] iommu/omap: cleanup: remove a redundant statement Ohad Ben-Cohen
2011-09-02 17:32 ` Ohad Ben-Cohen
2011-09-02 17:32 ` Ohad Ben-Cohen
2011-09-02 17:32 ` [PATCH 3/7] iommu/core: use the existing IS_ALIGNED macro Ohad Ben-Cohen
2011-09-02 17:32 ` Ohad Ben-Cohen
2011-09-02 17:32 ` Ohad Ben-Cohen
2011-09-02 17:32 ` [PATCH 4/7] iommu/omap: ->unmap() should return order of unmapped page Ohad Ben-Cohen
2011-09-02 17:32 ` Ohad Ben-Cohen
2011-09-02 17:32 ` Ohad Ben-Cohen
2011-09-02 17:32 ` [PATCH 5/7] iommu/msm: " Ohad Ben-Cohen
2011-09-02 17:32 ` Ohad Ben-Cohen
2011-09-02 17:32 ` Ohad Ben-Cohen
2011-09-02 18:36 ` David Brown
2011-09-02 18:36 ` David Brown
2011-09-02 18:36 ` David Brown
2011-09-02 17:32 ` [RFC 6/7] iommu/core: add fault reporting Ohad Ben-Cohen
2011-09-02 17:32 ` Ohad Ben-Cohen
2011-09-02 17:32 ` Ohad Ben-Cohen
2011-09-05 10:00 ` Roedel, Joerg
2011-09-05 10:00 ` Roedel, Joerg
2011-09-05 10:00 ` Roedel, Joerg
2011-09-07 16:36 ` Ohad Ben-Cohen
2011-09-07 16:36 ` Ohad Ben-Cohen
2011-09-07 16:36 ` Ohad Ben-Cohen
2011-09-02 17:32 ` [RFC 7/7] iommu/core: split mapping to page sizes as supported by the hardware Ohad Ben-Cohen
2011-09-02 17:32 ` Ohad Ben-Cohen
2011-09-02 17:32 ` Ohad Ben-Cohen
2011-09-07 1:30 ` KyongHo Cho
2011-09-07 1:30 ` KyongHo Cho
2011-09-07 6:01 ` Ohad Ben-Cohen
2011-09-07 6:01 ` Ohad Ben-Cohen
2011-09-07 8:05 ` KyongHo Cho
2011-09-07 8:05 ` KyongHo Cho
2011-09-07 9:16 ` Ohad Ben-Cohen
2011-09-07 9:16 ` Ohad Ben-Cohen
2011-09-08 12:51 ` KyongHo Cho [this message]
2011-09-08 12:51 ` KyongHo Cho
2011-09-08 14:03 ` Ohad Ben-Cohen
2011-09-08 14:03 ` Ohad Ben-Cohen
2011-09-07 9:49 ` Ohad Ben-Cohen
2011-09-07 9:49 ` Ohad Ben-Cohen
2011-09-06 10:15 ` [PATCH/RFC 0/7] iommu: fixes & extensions Roedel, Joerg
2011-09-06 10:15 ` Roedel, Joerg
2011-09-06 10:15 ` Roedel, Joerg
2011-09-06 11:28 ` Ohad Ben-Cohen
2011-09-06 11:28 ` Ohad Ben-Cohen
2011-09-06 11:28 ` Ohad Ben-Cohen
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