lkml.org 
[lkml]   [2020]   [Mar]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH v1] perf record: fix binding of AIO user space buffers to nodes
Em Thu, Mar 12, 2020 at 07:09:56PM +0300, Alexey Budankov escreveu:
>
> On 12.03.2020 17:31, Arnaldo Carvalho de Melo wrote:
> > Em Thu, Mar 12, 2020 at 03:21:45PM +0300, Alexey Budankov escreveu:
> >>
> >> Correct maxnode parameter value passed to mbind() syscall to be
> >> the amount of node mask bits to analyze plus 1. Dynamically allocate
> >> node mask memory depending on the index of node of cpu being profiled.
> >> Fixes: c44a8b44ca9f ("perf record: Bind the AIO user space buffers to nodes")
> >> Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
> >> ---
> >> tools/perf/util/mmap.c | 21 +++++++++++++++------
> >> 1 file changed, 15 insertions(+), 6 deletions(-)
> >>
> >> diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
> >> index 3b664fa673a6..6d604cd67a95 100644
> >> --- a/tools/perf/util/mmap.c
> >> +++ b/tools/perf/util/mmap.c
> >> @@ -98,20 +98,29 @@ static int perf_mmap__aio_bind(struct mmap *map, int idx, int cpu, int affinity)
> >> {
> >> void *data;
> >> size_t mmap_len;
> >> - unsigned long node_mask;
> >> + unsigned long *node_mask;
> >> + unsigned long node_index;
> >> + int err = 0;
> >>
> >> if (affinity != PERF_AFFINITY_SYS && cpu__max_node() > 1) {
> >> data = map->aio.data[idx];
> >> mmap_len = mmap__mmap_len(map);
> >> - node_mask = 1UL << cpu__get_node(cpu);
> >> - if (mbind(data, mmap_len, MPOL_BIND, &node_mask, 1, 0)) {
> >> - pr_err("Failed to bind [%p-%p] AIO buffer to node %d: error %m\n",
> >> - data, data + mmap_len, cpu__get_node(cpu));
> >> + node_index = cpu__get_node(cpu);
> >> + node_mask = bitmap_alloc(node_index + 1);
> >> + if (!node_mask) {
> >> + pr_err("Failed to allocate node mask for mbind: error %m\n");
> >> return -1;
> >> }
> >> + set_bit(node_index, node_mask);
> >> + if (mbind(data, mmap_len, MPOL_BIND, node_mask, node_index + 1 + 1/*nr_bits + 1*/, 0)) {
> >
> > ^^^^^^^^^^^^^^
> > Leftover?
>
> Intentionally put it here to document kernel behavior for mbind() syscall
> because currently it is different from the man page [1] documented:
>
> "nodemask points to a bit mask of nodes containing up to maxnode bits.
> The bit mask size is rounded to the next multiple of sizeof(unsigned
> long), but the kernel will use bits only up to maxnode. A NULL value
> of nodemask or a maxnode value of zero specifies the empty set of
> nodes. If the value of maxnode is zero, the nodemask argument is
> ignored. Where a nodemask is required, it must contain at least one
> node that is on-line, allowed by the thread's current cpuset context
> (unless the MPOL_F_STATIC_NODES mode flag is specified), and contains
> memory."

Ok, will add the above as a comment above the line with that comment.

> ~Alexey
>
> [1] http://man7.org/linux/man-pages/man2/mbind.2.html

--

- Arnaldo

\
 
 \ /
  Last update: 2020-03-12 18:13    [W:0.060 / U:3.748 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site