korg/linux
0
0
Fork 0
mirror of https://mirrors.bfsu.edu.cn/git/linux.git synced 2024-12-14 14:34:28 +08:00
Code Issues Packages Projects Releases Wiki Activity
1,199,785 Commits 113 Branches 5,294 Tags 3.6 GiB
C 97.5%
Assembly 1%
Shell 0.6%
Python 0.3%
Makefile 0.3%
791c2b17fb
Go to file
Robin Murphy 791c2b17fb iommu: Optimise PCI SAC address trick 
Per the reasoning in commit 4bf7fda4dc ("iommu/dma: Add config for
PCI SAC address trick") and its subsequent revert, this mechanism no
longer serves its original purpose, but now only works around broken
hardware/drivers in a way that is unfortunately too impactful to remove.

This does not, however, prevent us from solving the performance impact
which that workaround has on large-scale systems that don't need it.
Once the 32-bit IOVA space fills up and a workload starts allocating and
freeing on both sides of the boundary, the opportunistic SAC allocation
can then end up spending significant time hunting down scattered
fragments of free 32-bit space, or just reestablishing max32_alloc_size.
This can easily be exacerbated by a change in allocation pattern, such
as by changing the network MTU, which can increase pressure on the
32-bit space by leaving a large quantity of cached IOVAs which are now
the wrong size to be recycled, but also won't be freed since the
non-opportunistic allocations can still be satisfied from the whole
64-bit space without triggering the reclaim path.

However, in the context of a workaround where smaller DMA addresses
aren't simply a preference but a necessity, if we get to that point at
all then in fact it's already the endgame. The nature of the allocator
is currently such that the first IOVA we give to a device after the
32-bit space runs out will be the highest possible address for that
device, ever. If that works, then great, we know we can optimise for
speed by always allocating from the full range. And if it doesn't, then
the worst has already happened and any brokenness is now showing, so
there's little point in continuing to try to hide it.

To that end, implement a flag to refine the SAC business into a
per-device policy that can automatically get itself out of the way if
and when it stops being useful.

CC: Linus Torvalds <torvalds@linux-foundation.org>
CC: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Tested-by: Vasant Hegde <vasant.hegde@amd.com>
Tested-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/b8502b115b915d2a3fabde367e099e39106686c8.1681392791.git.robin.murphy@arm.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2023-07-14 16:14:17 +02:00
arch - Do FPU AP initialization on Xen PV too which got missed by the recent 2023-07-09 10:13:32 -07:00
block block-6.5-2023-07-03 2023-07-03 18:48:38 -07:00
certs KEYS: Add missing function documentation 2023-04-24 16:15:52 +03:00
crypto This update includes the following changes: 2023-06-30 21:27:13 -07:00
Documentation Fixes for pci_clean_master, error handling in driver inits, and various 2023-07-09 09:35:51 -07:00
drivers iommu: Optimise PCI SAC address trick 2023-07-14 16:14:17 +02:00
fs Minor cleanups for 6.5: 2023-07-09 09:50:42 -07:00
include iommu: Optimise PCI SAC address trick 2023-07-14 16:14:17 +02:00
init Kbuild updates for v6.5 2023-07-01 09:24:31 -07:00
io_uring io_uring-6.5-2023-07-03 2023-07-03 18:43:10 -07:00
ipc Merge branch 'work.namespace' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2023-02-24 19:20:07 -08:00
kernel dma-mapping fixes for Linux 6.5 2023-07-09 10:24:22 -07:00
lib 16 hotfixes. Six are cc:stable and the remainder address post-6.4 issues. 2023-07-08 14:30:25 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm: lock newly mapped VMA with corrected ordering 2023-07-08 16:44:11 -07:00
net Including fixes from bluetooth, bpf and wireguard. 2023-07-05 15:44:45 -07:00
rust rust: error: impl Debug for Error with errname() integration 2023-06-13 01:24:42 +02:00
samples Including fixes from bluetooth, bpf and wireguard. 2023-07-05 15:44:45 -07:00
scripts A half-dozen late arriving docs patches. They are mostly fixes, but we 2023-07-06 22:15:38 -07:00
security + Bug Fixes 2023-07-07 09:55:31 -07:00
sound sound fixes for 6.5-rc1 2023-07-07 15:40:17 -07:00
tools perf tools changes and fixes for v6.5: 2nd batch 2023-07-08 10:21:51 -07:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt ARM64: 2023-07-03 15:32:22 -07:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Revert ".gitignore: ignore *.cover and *.mbx" 2023-07-04 15:05:12 -07:00
.mailmap 16 hotfixes. Six are cc:stable and the remainder address post-6.4 issues. 2023-07-08 14:30:25 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS - Address -Wmissing-prototype warnings 2023-06-26 16:43:54 -07:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS 2: Electric Boogaloo 2023-07-09 10:29:53 -07:00
Makefile Linux 6.5-rc1 2023-07-09 13:53:13 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.