openwrt/config
Rafał Miłecki abc5b28db1 bcm53xx: use -falign-functions=32 for kernel compilation
Northstar SoCs have pretty small CPU caches and their performance is
heavily affected by cache hits & misses. It means that all kind of
random code changes can affect performance as they often reorganize
(change alignment & possibly reorder) kernel symbols.

It was discussed in ARM / net mailinglists:
1. ARM router NAT performance affected by random/unrelated commits [1] [2]
2. Optimizing kernel compilation / alignments for network performance [3] [4]

It seems that -falign-functions can be used as a partial workaround. It
doesn't solve all cases (e.g. documented watchdog one [5]) but it surely
helps with many of them.

A complete long term solution may be PGO (profile-guided optimization)
but it isn't available at this point.

[1] https://lkml.org/lkml/2019/5/21/349
[2] https://www.spinics.net/lists/linux-block/msg40624.html
[3] https://lore.kernel.org/linux-arm-kernel/066fc320-dc04-11a4-476e-b0d11f3b17e6@gmail.com/T/
[4] https://www.spinics.net/lists/netdev/msg816103.html
[5] http://lists.openwrt.org/pipermail/openwrt-devel/2022-July/038989.html

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
2022-07-03 13:59:12 +02:00
..
check-uname.sh build: add HOST_OS_LINUX and HOST_OS_MACOS config symbols 2021-11-01 16:37:52 +01:00
Config-build.in config: build: cleanup whitespace issue 2022-02-19 13:10:01 +01:00
Config-devel.in bcm53xx: use -falign-functions=32 for kernel compilation 2022-07-03 13:59:12 +02:00
Config-images.in uml: make use of 'rootfs-part' feature 2022-01-23 19:48:31 +00:00
Config-kernel.in kernel: add KERNEL_BPF_EVENTS config option 2022-05-18 13:32:06 +03:00