mirror of
https://github.com/torvalds/linux.git
synced 2026-07-28 01:55:51 +02:00
Linux kernel source tree
f8a55d5e71
Cpus serving NIC interrupts and specifically TX completions are often trapped in also restarting a busy qdisc (because qdisc was stopped by BQL or the driver's own flow control). When they call netdev_tx_completed_queue() or netif_tx_wake_queue(), they call __netif_schedule() so that the queue can be run later from net_tx_action() (involving NET_TX_SOFTIRQ) Quite often, by the time the cpu reaches net_tx_action(), another cpu grabbed the qdisc spinlock from __dev_xmit_skb(), and we spend too much time spinning on this lock. We can detect in __netif_schedule() if a cpu is already at a specific point in __dev_xmit_skb() where we have the guarantee the queue will be run. This patch gives a 13 % increase of throughput on an IDPF NIC (200Gbit), 32 TX qeues, sending UDP packets of 120 bytes. This also helps __qdisc_run() to not force a NET_TX_SOFTIRQ if another thread is waiting in __dev_xmit_skb() Before: sar -n DEV 5 5|grep eth1|grep Average Average: eth1 1496.44 52191462.56 210.00 13369396.90 0.00 0.00 0.00 54.76 After: sar -n DEV 5 5|grep eth1|grep Average Average: eth1 1457.88 59363099.96 205.08 15206384.35 0.00 0.00 0.00 62.29 Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com> Link: https://patch.msgid.link/20251017145334.3016097-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .clippy.toml | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .pylintrc | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| 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 reStructuredText 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.