diff options
| author | Karel Zak | 2011-03-31 12:55:13 +0200 |
|---|---|---|
| committer | Karel Zak | 2011-03-31 12:55:13 +0200 |
| commit | e282eec2a259903a02841f516b7778a1f639d8ff (patch) | |
| tree | 54eb17c5d16cba8e87815c8011d01265fe0dc3b8 /sys-utils/lscpu.c | |
| parent | login: fix checktty test to compile with old glibc (diff) | |
| download | kernel-qcow2-util-linux-e282eec2a259903a02841f516b7778a1f639d8ff.tar.gz kernel-qcow2-util-linux-e282eec2a259903a02841f516b7778a1f639d8ff.tar.xz kernel-qcow2-util-linux-e282eec2a259903a02841f516b7778a1f639d8ff.zip | |
lscpu: fix threads-per-core calculation
On Thu, Mar 24, 2011 at 01:45:34PM +0100, Jan Engelhardt wrote:
> On a 24-thread/6-core SPARC T1, lscpu would wrongly output "5
> threads per core".
>
> It seems that the 6c T1 is simply an 8c T1 where 2c are disabled
> (offering a lesser model for a lower price, and all that marketing
> fluff). So the machine description header of the 6c T1 reports 32
> threads, but only goes on to provide 24 elements thereafter, which
> is why Linux will report threads 24-31 as "offline". So far so good.
>
> But lscpu would take the number of all (online and offline) threads
> (32) and divides it by the number of online cores (6), which yields
> an odd 5.33 threads/core.
>
> Simply pick the number of online threads.
Based on Jan's patch.
Reported-by: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: Karel Zak <kzak@redhat.com>
Diffstat (limited to 'sys-utils/lscpu.c')
| -rw-r--r-- | sys-utils/lscpu.c | 20 |
1 files changed, 14 insertions, 6 deletions
diff --git a/sys-utils/lscpu.c b/sys-utils/lscpu.c index 79c6857e2..c3bb536cd 100644 --- a/sys-utils/lscpu.c +++ b/sys-utils/lscpu.c @@ -113,15 +113,15 @@ struct lscpu_desc { /* sockets -- based on core_siblings (internal kernel map of cpuX's * hardware threads within the same physical_package_id (socket)) */ - int nsockets; /* number of all sockets */ + int nsockets; /* number of all online sockets */ cpu_set_t **socketmaps; /* unique core_siblings */ /* cores -- based on thread_siblings (internel kernel map of cpuX's * hardware threads within the same core as cpuX) */ - int ncores; /* number of all cores */ + int ncores; /* number of all online cores */ cpu_set_t **coremaps; /* unique thread_siblings */ - int nthreads; /* number of threads */ + int nthreads; /* number of online threads */ int ncaches; struct cpu_cache *caches; @@ -415,8 +415,11 @@ read_basicinfo(struct lscpu_desc *desc) maxcpus = desc->ncpus > 2048 ? desc->ncpus : 2048; /* get mask for online CPUs */ - if (path_exist(_PATH_SYS_SYSTEM "/cpu/online")) + if (path_exist(_PATH_SYS_SYSTEM "/cpu/online")) { + size_t setsize = CPU_ALLOC_SIZE(maxcpus); desc->online = path_cpulist(_PATH_SYS_SYSTEM "/cpu/online"); + desc->nthreads = CPU_COUNT_S(setsize, desc->online); + } } static int @@ -586,8 +589,13 @@ read_topology(struct lscpu_desc *desc, int num) ncores = CPU_COUNT_S(setsize, core_siblings) / nthreads; /* number of sockets */ nsockets = desc->ncpus / nthreads / ncores; - /* all threads */ - desc->nthreads = nsockets * ncores * nthreads; + + /* all threads, see also read_basicinfo() + * -- this is fallback for kernels where is not + * /sys/devices/system/cpu/online. + */ + if (!desc->nthreads) + desc->nthreads = nsockets * ncores * nthreads; desc->socketmaps = calloc(nsockets, sizeof(cpu_set_t *)); if (!desc->socketmaps) |