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Vladimir Oltean 97b45d1b13 net: mscc: ocelot: fix stats region batching 
[ Upstream commit 6acc72a43e ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2023-03-30 12:51:20 +02:00
arch arm64: dts: imx93: add missing #address-cells and #size-cells to i2c nodes 2023-03-30 12:50:51 +02:00
block block: count 'ios' and 'sectors' when io is done for bio-based device 2023-03-22 13:37:50 +01:00
certs certs: Fix build error when PKCS#11 URI contains semicolon 2023-01-31 17:53:01 +09:00
crypto crypto: rsa-pkcs1pad - Use akcipher_request_complete 2023-03-10 09:28:18 +01:00
Documentation docs: Correct missing "d_" prefix for dentry_operations member d_weak_revalidate 2023-03-22 13:37:42 +01:00
drivers net: mscc: ocelot: fix stats region batching 2023-03-30 12:51:20 +02:00
fs nfsd: don't replace page in rq_pages if it's a continuation of last page 2023-03-30 12:50:53 +02:00
include net: stmmac: Fix for mismatched host/device DMA address width 2023-03-30 12:50:54 +02:00
init Kbuild fixes for v6.2 (3rd) 2023-01-21 10:56:37 -08:00
io_uring io_uring/msg_ring: let target know allocated index 2023-03-22 13:38:08 +01:00
ipc Non-MM patches for 6.2-rc1. 2022-12-12 17:28:58 -08:00
kernel bpf: Adjust insufficient default bpf_jit_limit 2023-03-30 12:51:19 +02:00
lib cpuidle: lib/bug: Disable rcu_is_watching() during WARN/BUG 2023-03-10 09:29:06 +01:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm: teach mincore_hugetlb about pte markers 2023-03-22 13:38:07 +01:00
net erspan: do not use skb_mac_header() in ndo_start_xmit() 2023-03-30 12:51:20 +02:00
rust rust: print: avoid evaluating arguments in pr_* macros in unsafe blocks 2023-01-16 00:54:35 +01:00
samples ftrace: Export ftrace_free_filter() to modules 2023-01-24 11:20:58 -05:00
scripts kconfig: Update config changed flag before calling callback 2023-03-22 13:37:55 +01:00
security keys: Do not cache key in task struct if key is requested from kernel thread 2023-03-30 12:50:57 +02:00
sound ASoC: qcom: q6prm: fix incorrect clk_root passed to ADSP 2023-03-22 13:38:08 +01:00
tools bootconfig: Fix testcase to increase max node 2023-03-30 12:50:57 +02:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt KVM: Register /dev/kvm as the _very_ last thing during initialization 2023-03-10 09:29:33 +01:00
.clang-format iommufd for 6.2 2022-12-14 09:15:43 -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 dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore *.rpm 2022-12-30 17:22:14 +09:00
.mailmap 12 hotfixes, mostly against mm/. Five of these fixes are cc:stable. 2023-02-13 14:09:20 -08:00
.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 MAINTAINERS: update SCTP maintainers 2023-02-02 11:35:33 -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 audit: update the mailing list in MAINTAINERS 2023-02-25 11:13:29 +01:00
Makefile Linux 6.2.8 2023-03-22 13:38:11 +01:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.