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BUG/MEDIUM: config: fix cpu-map notation with both process and threads

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The application of a cpu-map statement with both process and threads
is broken (P-Q/1 or 1/P-Q notation).

For example, before the fix, when using P-Q/1, proc_t1 would be updated.
Then it would be AND'ed with thread which is still 0 and thus does
nothing.

Another problem is when using 1/1[-Q], thread[0] is defined. But if
there is multiple processes, every processes will use this define
affinity even if it should be applied only to 1st process.

The solution to the fix is a little bit too complex for my taste and
there is maybe a simpler solution but I did not wish to break the
storage of global.cpu_map, as it is quite painful to test all the
use-cases. Besides, this code will probably be clean up when
multiprocess support removed on the future version.

Let's try to explain my logic.

* either haproxy runs in multiprocess or multithread mode. If on
  multiprocess, we should consider proc_t1 (P-Q/1 notation). If on
  multithread, we should consider thread (1/P-Q notation). However
  during parsing, the final number of processes or threads is unknown,
  thus we have to consider the two possibilities.

* there is a special case for the first thread / first process which is
  present in both execution modes. And as a matter of fact cpu-map 1 or
  1/1 notation represents the same thing. Thus, thread[0] and proc_t1[0]
  represents the same thing. To solve this problem, only thread[0] is
  used for this special case.

This fix must be backported up to 2.0.
This commit is contained in:
Amaury Denoyelle 2021-04-15 16:29:58 +02:00
parent 580727f3af
commit af02c57406
2 changed files with 23 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
src/cfgparse-global.c
View File

@ -1110,22 +1110,34 @@ int cfg_parse_global(const char *file, int linenum, char **args, int kwm)
}
}
} else {
/* Mapping at the thread level. All threads are retained
* for process 1, and only thread 1 is retained for other
* processes.
/* Mapping at the thread level.
* Either proc and/or thread must be 1 and only 1. All
* other combinations are silently ignored.
*/
if (thread == 0x1) {
int val;
/* first thread, iterate on processes. E.g. cpu-map 1-4/1 0-3 */
for (i = n = 0; i < MAX_PROCS; i++) {
/* No mapping for this process */
if (!(proc & (1UL << i)))
continue;
if (!autoinc)
global.cpu_map.proc_t1[i] = cpus;
if (!autoinc) {
val = cpus;
}
else {
n += my_ffsl(cpus >> n);
global.cpu_map.proc_t1[i] = (1UL << (n-1));
val = 1UL << (n - 1);
}
/* For first process, thread[0] is used.
* Use proc_t1[N] for all others
*/
if (!i)
global.cpu_map.thread[0] = val;
else
global.cpu_map.proc_t1[i] = val;
}
}

7
src/haproxy.c
View File

@ -3178,8 +3178,11 @@ int main(int argc, char **argv)
#ifdef USE_CPU_AFFINITY
/* Now the CPU affinity for all threads */
if (global.cpu_map.proc_t1[relative_pid-1])
global.cpu_map.thread[0] &= global.cpu_map.proc_t1[relative_pid-1];
/* If on multiprocess, use proc_t1 except for the first process.
*/
if ((relative_pid - 1) > 0)
global.cpu_map.thread[0] = global.cpu_map.proc_t1[relative_pid-1];
for (i = 0; i < global.nbthread; i++) {
if (global.cpu_map.proc[relative_pid-1])