mirror of
https://github.com/hardkernel/linux.git
synced 2026-06-10 21:07:02 +09:00
c55659cd14
[ Upstream commit0d87308cca] In commit14bd9a607f("iommu/iova: Separate atomic variables to improve performance") Jinyu Qi identified that the atomic_cmpxchg() in queue_iova() was causing a performance loss and moved critical fields so that the false sharing would not impact them. However, avoiding the false sharing in the first place seems easy. We should attempt the atomic_cmpxchg() no more than 100 times per second. Adding an atomic_read() will keep the cache line mostly shared. This false sharing came with commit9a005a800a("iommu/iova: Add flush timer"). Signed-off-by: Eric Dumazet <edumazet@google.com> Fixes:9a005a800a('iommu/iova: Add flush timer') Cc: Jinyu Qi <jinyuqi@huawei.com> Cc: Joerg Roedel <jroedel@suse.de> Acked-by: Robin Murphy <robin.murphy@arm.com> Signed-off-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Sasha Levin <sashal@kernel.org>
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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.