Re: qemu, numa: non-contiguous cpusets

From: Paolo Bonzini
Date: Mon Sep 30 2013 - 05:05:28 EST


Il 29/09/2013 17:10, Borislav Petkov ha scritto:
> Btw,
>
> while I got your attention, on a not-really related topic: how do we
> feel about adding support for specifying a non-contiguous set of cpus
> for a numa node in qemu with the -numa option? I.e., like this, for
> example:
>
> x86_64-softmmu/qemu-system-x86_64 -smp 8 -numa node,nodeid=0,cpus=0\;2\;4-5 -numa node,nodeid=1,cpus=1\;3\;6-7

I think there are already patches on the list to do that, as part of the
NUMA memory binding series from Wanlong Gao.

Paolo

> The ';' needs to be escaped from the shell but I'm open for better
> suggestions.
>
> Here's a diff:
>
> ---
> diff --git a/vl.c b/vl.c
> index 4e709d5c1c20..82a6c8451fb0 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -1261,9 +1261,27 @@ char *get_boot_devices_list(size_t *size)
> return list;
> }
>
> +static int __numa_set_cpus(unsigned long *map, int start, int end)
> +{
> + if (end >= MAX_CPUMASK_BITS) {
> + end = MAX_CPUMASK_BITS - 1;
> + fprintf(stderr,
> + "qemu: NUMA: A max of %d VCPUs are supported\n",
> + MAX_CPUMASK_BITS);
> + return -EINVAL;
> + }
> +
> + if (end < start) {
> + return -EINVAL;
> + }
> +
> + bitmap_set(map, start, end-start+1);
> + return 0;
> +}
> +
> static void numa_node_parse_cpus(int nodenr, const char *cpus)
> {
> - char *endptr;
> + char *endptr, *ptr = (char *)cpus;
> unsigned long long value, endvalue;
>
> /* Empty CPU range strings will be considered valid, they will simply
> @@ -1273,7 +1291,8 @@ static void numa_node_parse_cpus(int nodenr, const char *cpus)
> return;
> }
>
> - if (parse_uint(cpus, &value, &endptr, 10) < 0) {
> +fromthetop:
> + if (parse_uint(ptr, &value, &endptr, 10) < 0) {
> goto error;
> }
> if (*endptr == '-') {
> @@ -1282,22 +1301,22 @@ static void numa_node_parse_cpus(int nodenr, const char *cpus)
> }
> } else if (*endptr == '\0') {
> endvalue = value;
> - } else {
> - goto error;
> - }
> + } else if (*endptr == ';') {
> + if (__numa_set_cpus(node_cpumask[nodenr], value, value) < 0) {
> + goto error;
> + }
> + endptr++;
> + if (*endptr == '\0')
> + return;
>
> - if (endvalue >= MAX_CPUMASK_BITS) {
> - endvalue = MAX_CPUMASK_BITS - 1;
> - fprintf(stderr,
> - "qemu: NUMA: A max of %d VCPUs are supported\n",
> - MAX_CPUMASK_BITS);
> - }
> + ptr = endptr;
>
> - if (endvalue < value) {
> + goto fromthetop;
> + } else {
> goto error;
> }
>
> - bitmap_set(node_cpumask[nodenr], value, endvalue-value+1);
> + __numa_set_cpus(node_cpumask[nodenr], value, endvalue);
> return;
>
> error:
> --
>
> Thanks.
>

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