From: "H. Peter Anvin" <hpa@zytor.com>
To: Andi Kleen <andi@firstfloor.org>
Cc: Alexander Duyck <alexander.h.duyck@intel.com>,
konrad.wilk@oracle.com, tglx@linutronix.de, mingo@redhat.com,
rob@landley.net, akpm@linux-foundation.org, joerg.roedel@amd.com,
bhelgaas@google.com, shuahkhan@gmail.com,
linux-kernel@vger.kernel.org, devel@linuxdriverproject.org,
x86@kernel.org, torvalds@linux-foundation.org
Subject: Re: [RFC PATCH 0/7] Improve swiotlb performance by using physical addresses
Date: Sat, 06 Oct 2012 11:56:13 -0700 [thread overview]
Message-ID: <50707ECD.2070300@zytor.com> (raw)
In-Reply-To: <20121006175751.GS16230@one.firstfloor.org>
On 10/06/2012 10:57 AM, Andi Kleen wrote:
>
> Maybe it's just me, but that's somehow sad for one if() and a su
> btraction
>
> BTW __pa used to be a simple subtraction, the if () was just added to
> handle the few call sites for x86-64 that do __pa(&text_symbol).
> Maybe we should just go back to the old __pa_symbol() for those cases,
> then __pa could be the simple subtraction it used to was again
> and it could be inlined and everyone would be happy.
>
I wonder how much the double-mapping actually buys us, if we could get a
PIE-type memory model that doesn't try to create GOT references.
We would unambiguously lose out the cases where we currently can do
symbol(index) but I wonder how much the impact actually is.
The advantage would be that it would give us way more room to do kernel
space ASR.
-hpa
next prev parent reply other threads:[~2012-10-06 18:56 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-04 0:38 [RFC PATCH 0/7] Improve swiotlb performance by using physical addresses Alexander Duyck
2012-10-04 0:38 ` [RFC PATCH 1/7] swiotlb: Instead of tracking the end of the swiotlb region just calculate it Alexander Duyck
2012-10-04 13:01 ` Konrad Rzeszutek Wilk
2012-10-04 15:54 ` Alexander Duyck
2012-10-04 16:31 ` Konrad Rzeszutek Wilk
2012-10-04 0:38 ` [RFC PATCH 2/7] swiotlb: Make io_tlb_start a physical address instead of a virtual address Alexander Duyck
2012-10-04 13:18 ` Konrad Rzeszutek Wilk
2012-10-04 17:11 ` Alexander Duyck
2012-10-04 17:19 ` Konrad Rzeszutek Wilk
2012-10-04 20:22 ` Alexander Duyck
2012-10-09 16:43 ` Konrad Rzeszutek Wilk
2012-10-09 19:11 ` Alexander Duyck
2012-10-04 0:38 ` [RFC PATCH 3/7] swiotlb: Make io_tlb_overflow_buffer a physical address Alexander Duyck
2012-10-04 0:39 ` [RFC PATCH 4/7] swiotlb: Return physical addresses when calling swiotlb_tbl_map_single Alexander Duyck
2012-10-04 0:39 ` [RFC PATCH 5/7] swiotlb: Use physical addresses for swiotlb_tbl_unmap_single Alexander Duyck
2012-10-04 0:39 ` [RFC PATCH 6/7] swiotlb: Use physical addresses instead of virtual in swiotlb_tbl_sync_single Alexander Duyck
2012-10-04 0:39 ` [RFC PATCH 7/7] swiotlb: Do not export swiotlb_bounce since there are no external consumers Alexander Duyck
2012-10-04 12:55 ` [RFC PATCH 0/7] Improve swiotlb performance by using physical addresses Konrad Rzeszutek Wilk
2012-10-04 15:50 ` Alexander Duyck
2012-10-04 13:33 ` Konrad Rzeszutek Wilk
2012-10-04 17:57 ` Alexander Duyck
2012-10-05 16:55 ` Andi Kleen
2012-10-05 19:35 ` Alexander Duyck
2012-10-05 20:02 ` Andi Kleen
2012-10-05 23:23 ` Alexander Duyck
2012-10-06 17:57 ` Andi Kleen
2012-10-06 18:56 ` H. Peter Anvin [this message]
2012-10-08 15:43 ` Alexander Duyck
2012-10-09 19:05 ` Alexander Duyck
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=50707ECD.2070300@zytor.com \
--to=hpa@zytor.com \
--cc=akpm@linux-foundation.org \
--cc=alexander.h.duyck@intel.com \
--cc=andi@firstfloor.org \
--cc=bhelgaas@google.com \
--cc=devel@linuxdriverproject.org \
--cc=joerg.roedel@amd.com \
--cc=konrad.wilk@oracle.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=rob@landley.net \
--cc=shuahkhan@gmail.com \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
--cc=x86@kernel.org \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.