On Wed, 2012-11-07 at 12:47 +0100, Karel Zak wrote:
> On Tue, Oct 23, 2012 at 01:49:46PM -0600, Toshi Kani wrote:
> > 1) The system has 4 CPUs
> > $ lscpu -a -e
> > CPU NODE SOCKET CORE L1d:L1i:L2 ONLINE
> > 0 0 0 0 0:0:0 yes
> > 1 0 1 1 1:1:1 yes
> > 2 0 2 2 2:2:2 yes
> > 3 0 3 3 3:3:3 yes
> >
> > 2) Eject cpu2
> > # echo 1 > /sys/bus/acpi/devices/LNXCPU:02/eject
> >
> > 3) lscpu no longer recognizes cpu3 after cpu2 is ejected
> > $ lscpu -a -e
> > CPU NODE SOCKET CORE L1d:L1i:L2 ONLINE
> > 0 0 0 0 0:0:0 yes
> > 1 0 1 1 1:1:1 yes
> >
> > The following changes are made to address this issue.
> > - Use maxcpus to allocate and parse bitmaps.
> > - Set desc->ncpu from cpu/present, which includes both on-line
> > and off-line CPUs.
>
> In the directory tests we have a dump from some strange machine
>
> tests/ts/lscpu/dumps/sparc64-UltraSparc-T1.tar.gz
>
> where is 32 /sys/devices/system/cpu/cpu[0-9]* subdirectories, but the
> present mask is 0-23, all the masks from the dump:
>
> present: 0-23
> possible: 0-31
> online: 0-23
> offline: 24-31
> count: 32 (means ls -d sys/devices/system/cpu/cpu[0-9]* | wc -l)
>
> strange, right? But I guess we can ignore this dump, according to
> kernel Documentation/cpu-hotplug.txt the cpu[0-9]* subdirectories
> have to follow the present mask. Maybe the dump is broken or so..
Hi Karel,
Thanks for the updated patch. It looks good. I have tested it on my
setup and it worked fine as well.
I agree that the present mask and cpu directories need to be consistent.
I looked at the kernel code and found the following change, which might
be the cause of this issue.
====
commit 9f13a1fd452f11c18004ba2422a6384b424ec8a9
Author: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Date: Tue Jan 10 03:04:32 2012 +0000
cpu: Register a generic CPU device on architectures that currently
do not
frv, h8300, m68k, microblaze, openrisc, score, um and xtensa
currently
do not register a CPU device. Add the config option
GENERIC_CPU_DEVICES
which causes a generic CPU device to be registered for each present
CPU,
and make all these architectures select it.
Richard Weinberger <richard@xxxxxx> covered UML and suggested using
per_cpu.
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
====
Hi Ben,
In the change log above, you described that a generic CPU device to be
registered for each "present" CPU. However, in the code below, it used
for_each_possible_cpu(), instead of for_each_present_cpu(). Is this
what you intended?
+static void __init cpu_dev_register_generic(void)
+{
+#ifdef CONFIG_GENERIC_CPU_DEVICES
+ int i;
+
+ for_each_possible_cpu(i) {
+ if (register_cpu(&per_cpu(cpu_devices, i), i))
+ panic("Failed to register CPU device");
+ }
+#endif
+}
+
Thanks,
-Toshi
> Note that many of our old dumps in the tests/ts/lscpu/dumps don't
> contain /sys/devices/system/cpu/{present,online,possible} masks, but
> I will drop these incomplete dumps.
>
> > - desc->coremaps = xcalloc(desc->ncpus, sizeof(cpu_set_t *));
> > - desc->socketmaps = xcalloc(desc->ncpus, sizeof(cpu_set_t *));
> > + desc->coremaps = xcalloc(maxcpus, sizeof(cpu_set_t *));
> > + desc->socketmaps = xcalloc(maxcpus, sizeof(cpu_set_t *));
>
> [...]
>
> > - for (i = 0; i < desc->ncpus; i++) {
> > + for (i = 0; i < maxcpus; i++) {
> > read_topology(desc, i);
> > read_cache(desc, i);
> > read_polarization(desc, i);
>
> What about to read /sys/devices/system/cpu/possible to determine the
> maximal possible number of CPUs on the machine. It seems like
> overkill to follow the maximal size of the cpu_set_t mask (=maxcpus).
>
> The "possible" mask is static and no affected by hot-plug.
>
> See the patch below.
>
> Karel
>
>
> diff --git a/sys-utils/lscpu.c b/sys-utils/lscpu.c
> index 25a0273..5b1a0af 100644
> --- a/sys-utils/lscpu.c
> +++ b/sys-utils/lscpu.c
> @@ -150,7 +150,9 @@ struct lscpu_desc {
> int dispatching; /* none, horizontal or vertical */
> int mode; /* rm, lm or/and tm */
>
> - int ncpus; /* number of CPUs */
> + int ncpuspos; /* maximal possible CPUs */
> + int ncpus; /* number of present CPUs */
> + cpu_set_t *present; /* mask with present CPUs */
> cpu_set_t *online; /* mask with online CPUs */
>
> int nnodes; /* number of NUMA modes */
> @@ -204,8 +206,11 @@ struct lscpu_modifier {
> static int maxcpus; /* size in bits of kernel cpu mask */
>
> #define is_cpu_online(_d, _cpu) \
> - ((_d) && (_d)->online ? \
> - CPU_ISSET_S((_cpu), CPU_ALLOC_SIZE(maxcpus), (_d)->online) : 0)
> + ((_d) && (_d)->online ? \
> + CPU_ISSET_S((_cpu), CPU_ALLOC_SIZE(maxcpus), (_d)->online) : 0)
> +#define is_cpu_present(_d, _cpu) \
> + ((_d) && (_d)->present ? \
> + CPU_ISSET_S((_cpu), CPU_ALLOC_SIZE(maxcpus), (_d)->present) : 0)
>
> /*
> * IDs
> @@ -334,16 +339,13 @@ read_basicinfo(struct lscpu_desc *desc, struct lscpu_modifier *mod)
> FILE *fp = path_fopen("r", 1, _PATH_PROC_CPUINFO);
> char buf[BUFSIZ];
> struct utsname utsbuf;
> + size_t setsize;
>
> /* architecture */
> if (uname(&utsbuf) == -1)
> err(EXIT_FAILURE, _("error: uname failed"));
> desc->arch = xstrdup(utsbuf.machine);
>
> - /* count CPU(s) */
> - while(path_exist(_PATH_SYS_SYSTEM "/cpu/cpu%d", desc->ncpus))
> - desc->ncpus++;
> -
> /* details */
> while (fgets(buf, sizeof(buf), fp) != NULL) {
> if (lookup(buf, "vendor", &desc->vendor)) ;
> @@ -391,11 +393,27 @@ read_basicinfo(struct lscpu_desc *desc, struct lscpu_modifier *mod)
> if (maxcpus <= 0)
> /* error or we are reading some /sys snapshot instead of the
> * real /sys, let's use any crazy number... */
> - maxcpus = desc->ncpus > 2048 ? desc->ncpus : 2048;
> + maxcpus = 2048;
> +
> + setsize = CPU_ALLOC_SIZE(maxcpus);
> +
> + if (path_exist(_PATH_SYS_SYSTEM "/cpu/possible")) {
> + cpu_set_t *tmp = path_cpulist(maxcpus, _PATH_SYS_SYSTEM "/cpu/possible");
> + desc->ncpuspos = CPU_COUNT_S(setsize, tmp);
> + cpuset_free(tmp);
> + } else
> + err(EXIT_FAILURE, _("failed to determine number of CPUs: %s"),
> + _PATH_SYS_SYSTEM "/cpu/possible");
> +
> +
> + /* get mask for present CPUs */
> + if (path_exist(_PATH_SYS_SYSTEM "/cpu/present")) {
> + desc->present = path_cpulist(maxcpus, _PATH_SYS_SYSTEM "/cpu/present");
> + desc->ncpus = CPU_COUNT_S(setsize, desc->present);
> + }
>
> /* get mask for online CPUs */
> if (path_exist(_PATH_SYS_SYSTEM "/cpu/online")) {
> - size_t setsize = CPU_ALLOC_SIZE(maxcpus);
> desc->online = path_cpulist(maxcpus, _PATH_SYS_SYSTEM "/cpu/online");
> desc->nthreads = CPU_COUNT_S(setsize, desc->online);
> }
> @@ -626,16 +644,16 @@ read_topology(struct lscpu_desc *desc, int num)
> */
> if (!desc->nthreads)
> desc->nthreads = nbooks * nsockets * ncores * nthreads;
> - /* For each map we make sure that it can have up to ncpus
> + /* For each map we make sure that it can have up to ncpuspos
> * entries. This is because we cannot reliably calculate the
> * number of cores, sockets and books on all architectures.
> * E.g. completely virtualized architectures like s390 may
> * have multiple sockets of different sizes.
> */
> - desc->coremaps = xcalloc(desc->ncpus, sizeof(cpu_set_t *));
> - desc->socketmaps = xcalloc(desc->ncpus, sizeof(cpu_set_t *));
> + desc->coremaps = xcalloc(desc->ncpuspos, sizeof(cpu_set_t *));
> + desc->socketmaps = xcalloc(desc->ncpuspos, sizeof(cpu_set_t *));
> if (book_siblings)
> - desc->bookmaps = xcalloc(desc->ncpus, sizeof(cpu_set_t *));
> + desc->bookmaps = xcalloc(desc->ncpuspos, sizeof(cpu_set_t *));
> }
>
> add_cpuset_to_array(desc->socketmaps, &desc->nsockets, core_siblings);
> @@ -653,7 +671,7 @@ read_polarization(struct lscpu_desc *desc, int num)
> if (!path_exist(_PATH_SYS_CPU "/cpu%d/polarization", num))
> return;
> if (!desc->polarization)
> - desc->polarization = xcalloc(desc->ncpus, sizeof(int));
> + desc->polarization = xcalloc(desc->ncpuspos, sizeof(int));
> path_getstr(mode, sizeof(mode), _PATH_SYS_CPU "/cpu%d/polarization", num);
> if (strncmp(mode, "vertical:low", sizeof(mode)) == 0)
> desc->polarization[num] = POLAR_VLOW;
> @@ -673,7 +691,7 @@ read_address(struct lscpu_desc *desc, int num)
> if (!path_exist(_PATH_SYS_CPU "/cpu%d/address", num))
> return;
> if (!desc->addresses)
> - desc->addresses = xcalloc(desc->ncpus, sizeof(int));
> + desc->addresses = xcalloc(desc->ncpuspos, sizeof(int));
> desc->addresses[num] = path_getnum(_PATH_SYS_CPU "/cpu%d/address", num);
> }
>
> @@ -683,7 +701,7 @@ read_configured(struct lscpu_desc *desc, int num)
> if (!path_exist(_PATH_SYS_CPU "/cpu%d/configure", num))
> return;
> if (!desc->configured)
> - desc->configured = xcalloc(desc->ncpus, sizeof(int));
> + desc->configured = xcalloc(desc->ncpuspos, sizeof(int));
> desc->configured[num] = path_getnum(_PATH_SYS_CPU "/cpu%d/configure", num);
> }
>
> @@ -756,7 +774,7 @@ read_cache(struct lscpu_desc *desc, int num)
> num, i);
>
> if (!ca->sharedmaps)
> - ca->sharedmaps = xcalloc(desc->ncpus, sizeof(cpu_set_t *));
> + ca->sharedmaps = xcalloc(desc->ncpuspos, sizeof(cpu_set_t *));
> add_cpuset_to_array(ca->sharedmaps, &ca->nsharedmaps, map);
> }
> }
> @@ -982,13 +1000,15 @@ print_parsable(struct lscpu_desc *desc, int cols[], int ncols,
> /*
> * Data
> */
> - for (i = 0; i < desc->ncpus; i++) {
> + for (i = 0; i < desc->ncpuspos; i++) {
> int c;
>
> if (!mod->offline && desc->online && !is_cpu_online(desc, i))
> continue;
> if (!mod->online && desc->online && is_cpu_online(desc, i))
> continue;
> + if (desc->present && !is_cpu_present(desc, i))
> + continue;
> for (c = 0; c < ncols; c++) {
> if (mod->compat && cols[c] == COL_CACHE) {
> if (!desc->ncaches)
> @@ -1026,7 +1046,7 @@ print_readable(struct lscpu_desc *desc, int cols[], int ncols,
> tt_define_column(tt, xstrdup(data), 0, 0);
> }
>
> - for (i = 0; i < desc->ncpus; i++) {
> + for (i = 0; i < desc->ncpuspos; i++) {
> int c;
> struct tt_line *line;
>
> @@ -1034,6 +1054,8 @@ print_readable(struct lscpu_desc *desc, int cols[], int ncols,
> continue;
> if (!mod->online && desc->online && is_cpu_online(desc, i))
> continue;
> + if (desc->present && !is_cpu_present(desc, i))
> + continue;
>
> line = tt_add_line(tt, NULL);
>
> @@ -1117,8 +1139,8 @@ print_summary(struct lscpu_desc *desc, struct lscpu_modifier *mod)
> if (!set)
> err(EXIT_FAILURE, _("failed to callocate cpu set"));
> CPU_ZERO_S(setsize, set);
> - for (i = 0; i < desc->ncpus; i++) {
> - if (!is_cpu_online(desc, i))
> + for (i = 0; i < desc->ncpuspos; i++) {
> + if (!is_cpu_online(desc, i) && is_cpu_present(desc, i))
> CPU_SET_S(i, setsize, set);
> }
> print_cpuset(mod->hex ? _("Off-line CPU(s) mask:") :
> @@ -1339,7 +1361,7 @@ int main(int argc, char *argv[])
>
> read_basicinfo(desc, mod);
>
> - for (i = 0; i < desc->ncpus; i++) {
> + for (i = 0; i < desc->ncpuspos; i++) {
> read_topology(desc, i);
> read_cache(desc, i);
> read_polarization(desc, i);
>
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