da8a58b56c
There are 2 problems wrt. cpu_topology_map on systems with sparse CPUs:
1. offline/absent CPUs will have their socket_id and core_id set to -1
which triggers:
"socket_id number is too big.You may need to upgrade the perf tool."
2. size of cpu_topology_map (perf_env.cpu[]) is allocated based on
_SC_NPROCESSORS_CONF, but can be indexed with CPU ids going above.
Users of perf_env.cpu[] are using CPU id as index. This can lead
to read beyond what was allocated:
==19991== Invalid read of size 4
==19991== at 0x490CEB: check_cpu_topology (topology.c:69)
==19991== by 0x490CEB: test_session_topology (topology.c:106)
...
For example:
_SC_NPROCESSORS_CONF == 16
available: 2 nodes (0-1)
node 0 cpus: 0 6 8 10 16 22 24 26
node 0 size: 12004 MB
node 0 free: 9470 MB
node 1 cpus: 1 7 9 11 23 25 27
node 1 size: 12093 MB
node 1 free: 9406 MB
node distances:
node 0 1
0: 10 20
1: 20 10
This patch changes HEADER_NRCPUS.nr_cpus_available from _SC_NPROCESSORS_CONF
to max_present_cpu and updates any user of cpu_topology_map to iterate
with nr_cpus_avail.
As a consequence HEADER_CPU_TOPOLOGY core_id and socket_id lists get longer,
but maintain compatibility with pre-patch state - index to cpu_topology_map is
CPU id.
perf test 36 -v
36: Session topology :
--- start ---
test child forked, pid 22211
templ file: /tmp/perf-test-gmdX5i
CPU 0, core 0, socket 0
CPU 1, core 0, socket 1
CPU 6, core 10, socket 0
CPU 7, core 10, socket 1
CPU 8, core 1, socket 0
CPU 9, core 1, socket 1
CPU 10, core 9, socket 0
CPU 11, core 9, socket 1
CPU 16, core 0, socket 0
CPU 22, core 10, socket 0
CPU 23, core 10, socket 1
CPU 24, core 1, socket 0
CPU 25, core 1, socket 1
CPU 26, core 9, socket 0
CPU 27, core 9, socket 1
test child finished with 0
---- end ----
Session topology: Ok
Signed-off-by: Jan Stancek <jstancek@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/d7c05c6445fca74a8442c2c73cfffd349c52c44f.1487146877.git.jstancek@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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README
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.