Messages in this thread Patch in this message | | | Date | Thu, 11 Feb 2021 10:20:18 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH 13/24] perf daemon: Allow only one daemon over base directory |
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Em Mon, Feb 08, 2021 at 09:08:57PM +0100, Jiri Olsa escreveu: > Add 'lock' file under daemon base and flock it, so only one > perf daemon can run on top of it. > > Each daemon tries to create and lock BASE/lock file, if it's > successful we are sure we're the only daemon running over > the BASE. > > Once daemon is finished, file descriptor to lock file is > closed and lock is released. > > Example: > > # cat ~/.perfconfig > [daemon] > base=/opt/perfdata > > [session-cycles] > run = -m 10M -e cycles --overwrite --switch-output -a > > [session-sched] > run = -m 20M -e sched:* --overwrite --switch-output -a > > Starting the daemon: > > # perf daemon start > > And try once more: > > # perf daemon start > failed: another perf daemon (pid 775594) owns /opt/perfdata > > will end up with an error, because there's already one running > on top of /opt/perfdata.
Had to add this:
Committer notes:
Provide lockf(F_TLOCK) when not available, i.e. transform:
lockf(fd, F_TLOCK, 0);
into:
flock(fd, LOCK_EX | LOCK_NB);
Which should be equivalent.
Noticed when cross building to some odd Android NDK.
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Patch:
[acme@five perf]$ git diff diff --git a/tools/perf/builtin-daemon.c b/tools/perf/builtin-daemon.c index 1c17c9e10ca6a656..2890573540f7d027 100644 --- a/tools/perf/builtin-daemon.c +++ b/tools/perf/builtin-daemon.c @@ -914,6 +914,20 @@ static int setup_config(struct daemon *daemon) return daemon->config_real ? 0 : -1; } +#ifndef F_TLOCK +#define F_TLOCK 2 + +#include <sys/file.h> + +static int lockf(int fd, int cmd, off_t len) +{ + if (cmd != F_TLOCK || len != 0) + return -1; + + return flock(fd, LOCK_EX | LOCK_NB); +} +#endif // F_TLOCK + /* * Each daemon tries to create and lock BASE/lock file, * if it's successful we are sure we're the only daemon [acme@five perf]$
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