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The struct zone is embedded in struct pglist_data which can be allocated
for each NUMA node early in the boot process. As it's not a slab object
nor a global lock, this was not symbolized.
Since the zone->lock is often contended, it'd be nice if we can
symbolize it. On NUMA systems, node_data array will have pointers for
struct pglist_data. By following the pointer, it can calculate the
address of each zone and its lock using BTF. On UMA, it can just use
contig_page_data and its zones.
The following example shows the zone lock contention at the end.
$ sudo ./perf lock con -abl -E 5 -- ./perf bench sched messaging
# Running 'sched/messaging' benchmark:
# 20 sender and receiver processes per group
# 10 groups == 400 processes run
Total time: 0.038 [sec]
contended total wait max wait avg wait address symbol
5167 18.17 ms 10.27 us 3.52 us ffff953340052d00 &kmem_cache_node (spinlock)
38 11.75 ms 465.49 us 309.13 us ffff95334060c480 &sock_inode_cache (spinlock)
3916 10.13 ms 10.43 us 2.59 us ffff953342aecb40 &kmem_cache_node (spinlock)
2963 10.02 ms 13.75 us 3.38 us ffff9533d2344098 &kmalloc-rnd-08-2k (spinlock)
216 5.05 ms 99.49 us 23.39 us ffff9542bf7d65d0 zone_lock (spinlock)
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <song@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: bpf@vger.kernel.org
Cc: linux-mm@kvack.org
Link: https://lore.kernel.org/r/20250401063055.7431-1-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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| 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.