Performed strace on one one of the apache children and its showing 24 seconds between two system calls.How can i determine what is the cause of this behavior.It looks like both children are taking almost same amound of time(24.7 and 23.92) seconds.
we are using apache prefork with php5 and mysql 5
/var/lib/php5/ is the php session folder
strace output of apache children1 with processid -20539
ps -u www-data | grep apache2 | awk '{print"-p " $1}' | xargs strace -o /strace/strace.log -ff -s4096 -r
20539 0.000064 close(13) = 0
20539 0.000060 open("/var/lib/php5/sess_9t2cvnvdoruh666rjpm515idm0", O_RDWR|O_CREAT, 0600) = 13
20539 0.000065 flock(13, LOCK_EX) = 0
20539 24.711888 fcntl(13, F_SETFD, FD_CLOEXEC) = 0
20539 0.000056 fstat(13, {st_mode=S_IFREG|0600, st_size=211, ...}) = 0
20539 0.000080 lseek(13, 0, SEEK_SET) = 0
strace output of apache children2 with processid - 20556
20556 0.000056 close(13) = 0
20556 0.000058 open("/var/lib/php5/sess_9t2cvnvdoruh666rjpm515idm0", O_RDWR|O_CREAT, 0600) = 13
20556 0.000062 flock(13, LOCK_EX) = 0
20556 23.928294 fcntl(13, F_SETFD, FD_CLOEXEC) = 0
20556 0.000055 fstat(13, {st_mode=S_IFREG|0600, st_size=211, ...}) = 0
20556 0.000083 lseek(13, 0, SEEK_SET) = 0
Can it be a problem with file that file descriptor(13) called?? is there anything wrong with my understanding of strace output.