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Filename Latest commit message Latest commit date
Cong Wang 1fbf1252df mlx5: use RCU lock in mlx5_eq_cq_get()
mlx5_eq_cq_get() is called in IRQ handler, the spinlock inside
gets a lot of contentions when we test some heavy workload
with 60 RX queues and 80 CPU's, and it is clearly shown in the
flame graph.

In fact, radix_tree_lookup() is perfectly fine with RCU read lock,
we don't have to take a spinlock on this hot path. This is pretty
much similar to commit 291c566a28
("net/mlx4_core: Fix racy CQ (Completion Queue) free"). Slow paths
are still serialized with the spinlock, and with synchronize_irq()
it should be safe to just move the fast path to RCU read lock.

This patch itself reduces the latency by about 50% for our memcached
workload on a 4.14 kernel we test. In upstream, as pointed out by Saeed,
this spinlock gets some rework in commit 02d92f7903
("net/mlx5: CQ Database per EQ"), so the difference could be smaller.

Cc: Saeed Mahameed <saeedm@mellanox.com>
Cc: Tariq Toukan <tariqt@mellanox.com>
Acked-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
2019-02-11 14:39:14 -08:00
arch ARM: SoC fixes 2019-01-14 10:34:14 +12:00
block block: fix kerneldoc comment for blk_attempt_plug_merge() 2019-01-09 15:29:08 -07:00
certs
crypto
Documentation ARM: SoC fixes 2019-01-14 10:34:14 +12:00
drivers mlx5: use RCU lock in mlx5_eq_cq_get() 2019-02-11 14:39:14 -08:00
firmware
fs for-5.0-rc1-tag 2019-01-14 05:55:51 +12:00
include net/mlx5: Set ODP SRQ support in firmware 2019-02-03 12:49:59 +02:00
init
ipc
kernel kernel/sys.c: Clarify that UNAME26 does not generate unique versions anymore 2019-01-14 10:38:03 +12:00
lib Kbuild late updates for v4.21 2019-01-06 16:33:10 -08:00
LICENSES
mm mm/mmu_notifier: mm/rmap.c: Fix a mmu_notifier range bug in try_to_unmap_one 2019-01-10 02:58:21 -08:00
net libceph: allow setting abort_on_full for rbd 2019-01-07 22:47:48 +01:00
samples samples/seccomp: Fix 32-bit build 2019-01-08 07:45:01 +01:00
scripts remove dma_zalloc_coherent 2019-01-12 10:52:40 -08:00
security
sound remove dma_zalloc_coherent 2019-01-12 10:52:40 -08:00
tools Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-01-11 09:44:05 -08:00
usr
virt KVM: validate userspace input in kvm_clear_dirty_log_protect() 2019-01-11 18:38:07 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild kbuild: use assignment instead of define ... endef for filechk_* rules 2019-01-06 10:22:35 +09:00
Kconfig
MAINTAINERS Staging driver fixes for 5.0-rc2 2019-01-14 05:49:35 +12:00
Makefile Linux 5.0-rc2 2019-01-14 10:41:12 +12:00
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.