Messages in this thread | | | Date | Thu, 11 Feb 2021 17:35:51 +0100 | From | Jiri Olsa <> | Subject | Re: [PATCH 13/24] perf daemon: Allow only one daemon over base directory |
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On Thu, Feb 11, 2021 at 10:20:18AM -0300, Arnaldo Carvalho de Melo wrote: > 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. > > ------ > > 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]$ >
nice, thanks
jirka
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