On Mon, Nov 16, 2009 at 04:49:30PM +0000, Daniel P. Berrange wrote:
> The cpu_set_t type can only cope with NR_CPUS <= 1024, beyond this
> it is neccessary to use alternate CPU_SET maps with a dynamically
> allocated CPU map
>
> * src/util/processinfo.c: Support new unlimited size CPU set type
> ---
> src/util/processinfo.c | 84 ++++++++++++++++++++++++++++++++++++++++++++++++
> 1 files changed, 84 insertions(+), 0 deletions(-)
>
> diff --git a/src/util/processinfo.c b/src/util/processinfo.c
> index aaffd88..a0dac34 100644
> --- a/src/util/processinfo.c
> +++ b/src/util/processinfo.c
> @@ -38,6 +38,48 @@ int virProcessInfoSetAffinity(pid_t pid,
> int maxcpu)
> {
> int i;
> +#ifdef CPU_ALLOC
> + /* New method dynamically allocates cpu mask, allowing unlimted cpus */
> + int numcpus = 1024;
> + size_t masklen;
> + cpu_set_t *mask;
> +
> + /* Not only may the statically allocated cpu_set_t be too small,
> + * but there is no way to ask the kernel what size is large enough.
> + * So you have no option but to pick a size, try, catch EINVAL,
> + * enlarge, and re-try.
> + *
> + * http://lkml.org/lkml/2009/7/28/620
> + */
Urgh ....
> +realloc:
> + masklen = CPU_ALLOC_SIZE(numcpus);
> + mask = CPU_ALLOC(numcpus);
> +
> + if (!mask) {
> + virReportOOMError(NULL);
> + return -1;
> + }
> +
> + CPU_ZERO_S(masklen, mask);
> + for (i = 0 ; i < maxcpu ; i++) {
> + if (VIR_CPU_USABLE(map, maplen, 0, i))
> + CPU_SET_S(i, masklen, mask);
> + }
> +
> + if (sched_setaffinity(pid, masklen, mask) < 0) {
> + CPU_FREE(mask);
> + if (errno == EINVAL &&
> + numcpus < (1024 << 8)) { /* 262144 cpus ought to be enough for anyone */
> + numcpus = numcpus << 2;
let's just
numcpus *= 2;
or
numcpus *= 4;
it's not like we want to shave a microsecond, makes code less readable.
> + goto realloc;
> + }
> + virReportSystemError(NULL, errno,
> + _("cannot set CPU affinity on process %d"), pid);
> + return -1;
> + }
> + CPU_FREE(mask);
> +#else
> + /* Legacy method uses a fixed size cpu mask, only allows upto 1024 cpus */
> cpu_set_t mask;
>
> CPU_ZERO(&mask);
> @@ -51,6 +93,7 @@ int virProcessInfoSetAffinity(pid_t pid,
> _("cannot set CPU affinity on process %d"), pid);
> return -1;
> }
> +#endif
>
> return 0;
> }
> @@ -61,6 +104,46 @@ int virProcessInfoGetAffinity(pid_t pid,
> int maxcpu)
> {
> int i;
> +#ifdef CPU_ALLOC
> + /* New method dynamically allocates cpu mask, allowing unlimted cpus */
> + int numcpus = 1024;
> + size_t masklen;
> + cpu_set_t *mask;
> +
> + /* Not only may the statically allocated cpu_set_t be too small,
> + * but there is no way to ask the kernel what size is large enough.
> + * So you have no option but to pick a size, try, catch EINVAL,
> + * enlarge, and re-try.
> + *
> + * http://lkml.org/lkml/2009/7/28/620
> + */
> +realloc:
> + masklen = CPU_ALLOC_SIZE(numcpus);
> + mask = CPU_ALLOC(numcpus);
> +
> + if (!mask) {
> + virReportOOMError(NULL);
> + return -1;
> + }
> +
> + CPU_ZERO_S(masklen, mask);
> + if (sched_getaffinity(pid, masklen, mask) < 0) {
> + CPU_FREE(mask);
> + if (errno == EINVAL &&
> + numcpus < (1024 << 8)) { /* 262144 cpus ought to be enough for anyone */
> + numcpus = numcpus << 2;
same
I would also make numcpus a static variable, so that you don't repeat he
loop each time you go though one of those APIs.
> + goto realloc;
> + }
> + virReportSystemError(NULL, errno,
> + _("cannot set CPU affinity on process %d"), pid);
> + return -1;
> + }
> +
> + for (i = 0 ; i < maxcpu ; i++)
> + if (CPU_ISSET_S(i, masklen, mask))
> + VIR_USE_CPU(map, i);
> +#else
> + /* Legacy method uses a fixed size cpu mask, only allows upto 1024 cpus */
> cpu_set_t mask;
>
> CPU_ZERO(&mask);
> @@ -73,6 +156,7 @@ int virProcessInfoGetAffinity(pid_t pid,
> for (i = 0 ; i < maxcpu ; i++)
> if (CPU_ISSET(i, &mask))
> VIR_USE_CPU(map, i);
> +#endif
>
> return 0;
> }
That patch sounds less urgent might be worth waiting past 0.7.3,
ACK though
Daniel
--
Daniel Veillard | libxml Gnome XML XSLT toolkit http://xmlsoft.org/
daniel@xxxxxxxxxxxx | Rpmfind RPM search engine http://rpmfind.net/
http://veillard.com/ | virtualization library http://libvirt.org/
--
Libvir-list mailing list
Libvir-list@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/libvir-list