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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>
This commit is contained in:
Karel Zak 2011-03-31 12:55:13 +02:00
parent f0fc846a53
commit e282eec2a2
1 changed files with 14 additions and 6 deletions
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20
sys-utils/lscpu.c
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@ -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)