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Vladimir Oltean 6acc72a43e net: mscc: ocelot: fix stats region batching
The blamed commit changed struct ocelot_stat_layout :: "u32 offset" to
"u32 reg".

However, "u32 reg" is not quite a register address, but an enum
ocelot_reg, which in itself encodes an enum ocelot_target target in the
upper bits, and an index into the ocelot->map[target][] array in the
lower bits.

So, whereas the previous code comparison between stats_layout[i].offset
and last + 1 was correct (because those "offsets" at the time were
32-bit relative addresses), the new code, comparing layout[i].reg to
last + 4 is not correct, because the "reg" here is an enum/index, not an
actual register address.

What we want to compare are indeed register addresses, but to do that,
we need to actually go through the same motions as
__ocelot_bulk_read_ix() itself.

With this bug, all statistics counters are deemed by
ocelot_prepare_stats_regions() as constituting their own region.
(Truncated) log on VSC9959 (Felix) below (prints added by me):

Before:

region of 1 contiguous counters starting with SYS:STAT:CNT[0x000]
region of 1 contiguous counters starting with SYS:STAT:CNT[0x001]
region of 1 contiguous counters starting with SYS:STAT:CNT[0x002]
...
region of 1 contiguous counters starting with SYS:STAT:CNT[0x041]
region of 1 contiguous counters starting with SYS:STAT:CNT[0x042]
region of 1 contiguous counters starting with SYS:STAT:CNT[0x080]
region of 1 contiguous counters starting with SYS:STAT:CNT[0x081]
...
region of 1 contiguous counters starting with SYS:STAT:CNT[0x0ac]
region of 1 contiguous counters starting with SYS:STAT:CNT[0x100]
region of 1 contiguous counters starting with SYS:STAT:CNT[0x101]
...
region of 1 contiguous counters starting with SYS:STAT:CNT[0x111]

After:

region of 67 contiguous counters starting with SYS:STAT:CNT[0x000]
region of 45 contiguous counters starting with SYS:STAT:CNT[0x080]
region of 18 contiguous counters starting with SYS:STAT:CNT[0x100]

Since commit d87b1c08f3 ("net: mscc: ocelot: use bulk reads for
stats") intended bulking as a performance improvement, and since now,
with trivial-sized regions, performance is even worse than without
bulking at all, this could easily qualify as a performance regression.

Fixes: d4c3676507 ("net: mscc: ocelot: keep ocelot_stat_layout by reg address, not offset")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Acked-by: Colin Foster <colin.foster@in-advantage.com>
Tested-by: Colin Foster <colin.foster@in-advantage.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-03-21 21:27:10 -07:00
arch xen: branch for v6.3-rc3 2023-03-17 10:45:49 -07:00
block block: remove obsolete config BLOCK_COMPAT 2023-03-16 09:35:44 -06:00
certs Kbuild updates for v6.3 2023-02-26 11:53:25 -08:00
crypto Networking changes for 6.3. 2023-02-21 18:24:12 -08:00
Documentation Including fixes from netfilter, wifi and ipsec. 2023-03-17 13:31:16 -07:00
drivers net: mscc: ocelot: fix stats region batching 2023-03-21 21:27:10 -07:00
fs seven cifs/smb3 client fixes, all also for stable 2023-03-16 15:06:16 -07:00
include net: stmmac: Fix for mismatched host/device DMA address width 2023-03-19 10:56:03 +00:00
init Kbuild updates for v6.3 2023-02-26 11:53:25 -08:00
io_uring io_uring/rsrc: fix folio accounting 2023-03-16 09:32:18 -06:00
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 sched_getaffinity: don't assume 'cpumask_size()' is fully initialized 2023-03-14 19:32:38 -07:00
lib Zstd fixes for v6.3 2023-03-14 17:03:25 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm/damon/paddr: fix folio_nr_pages() after folio_put() in damon_pa_mark_accessed_or_deactivate() 2023-03-07 17:04:55 -08:00
net erspan: do not use skb_mac_header() in ndo_start_xmit() 2023-03-21 21:16:26 -07:00
rust Rust fixes for 6.3-rc1 2023-03-03 14:51:15 -08:00
samples LoongArch changes for v6.3 2023-03-01 09:27:00 -08:00
scripts Remove Intel compiler support 2023-03-05 10:49:37 -08:00
security capability: just use a 'u64' instead of a 'u32[2]' array 2023-03-01 10:01:22 -08:00
sound ALSA: hda/ca0132: fixup buffer overrun at tuning_ctl_set() 2023-03-14 17:04:53 +01:00
tools Including fixes from netfilter, wifi and ipsec. 2023-03-17 13:31:16 -07:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt KVM/riscv changes for 6.3 2023-02-15 12:33:28 -05:00
.clang-format cpumask: re-introduce constant-sized cpumask optimizations 2023-03-05 14:30:34 -08:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for *.dtso files 2023-02-26 15:28:23 +09:00
.gitignore .gitignore: ignore *.cover and *.mbx 2023-02-05 18:51:22 +09:00
.mailmap Including fixes from netfilter, wifi and ipsec. 2023-03-17 13:31:16 -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 There is no particular theme here - mainly quick hits all over the tree. 2023-02-23 17:55:40 -08:00
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 Including fixes from netfilter, wifi and ipsec. 2023-03-17 13:31:16 -07:00
Makefile Linux 6.3-rc2 2023-03-12 16:36:44 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.