On Wed, Jan 19, 2022 at 4:27 PM HAGIO KAZUHITO(萩尾 一仁) <[email protected]> wrote:
> With some vmlinux e.g. RHEL9 ones, the first execution of the gdb ptype > command heavily consumes memory and time. The "ps -t" option uses it > in start_time_timespec() and it can be replaced with crash macros. > This can reduce about 1.4 GB memory and 6 seconds time comsumption in > the following test: > > $ echo "ps -t" | time crash vmlinux vmcore > > Without the patch: > 11.60user 0.43system 0:11.94elapsed 100%CPU (0avgtext+0avgdata > 1837964maxresident)k > 0inputs+400outputs (0major+413636minor)pagefaults 0swaps > > With the patch: > 5.40user 0.16system 0:05.46elapsed 101%CPU (0avgtext+0avgdata > 417896maxresident)k > 0inputs+384outputs (0major+41528minor)pagefaults 0swaps > > Although the ptype command and similar ones cannot be fully removed, > but removing some of them will make the use of crash safer, especially > for an automatic crash analyzer. > > Signed-off-by: Kazuhito Hagio <[email protected]> > --- > task.c | 25 +++++-------------------- > 1 file changed, 5 insertions(+), 20 deletions(-) > > diff --git a/task.c b/task.c > index 263a8344dd94..a79ed0d96fb5 100644 > --- a/task.c > +++ b/task.c > @@ -4662,8 +4662,6 @@ show_task_times(struct task_context *tcp, ulong > flags) > static int > start_time_timespec(void) > { > - char buf[BUFSIZE]; > - > switch(tt->flags & (TIMESPEC | NO_TIMESPEC | START_TIME_NSECS)) > { > case TIMESPEC: > @@ -4677,24 +4675,11 @@ start_time_timespec(void) > > tt->flags |= NO_TIMESPEC; > > - open_tmpfile(); > - sprintf(buf, "ptype struct task_struct"); > - if (!gdb_pass_through(buf, NULL, GNU_RETURN_ON_ERROR)) { > - close_tmpfile(); > - return FALSE; > - } > - > - rewind(pc->tmpfile); > - while (fgets(buf, BUFSIZE, pc->tmpfile)) { > - if (strstr(buf, "start_time;")) { > - if (strstr(buf, "struct timespec")) { > - tt->flags &= ~NO_TIMESPEC; > - tt->flags |= TIMESPEC; > - } > - } > - } > - > - close_tmpfile(); > + if (VALID_MEMBER(task_struct_start_time) && > + STREQ(MEMBER_TYPE_NAME("task_struct", "start_time"), > "timespec")) { > + tt->flags &= ~NO_TIMESPEC; > + tt->flags |= TIMESPEC; > + } > > if ((tt->flags & NO_TIMESPEC) && (SIZE(task_struct_start_time) == > 8)) { > tt->flags &= ~NO_TIMESPEC; > -- > 2.27.0 > For this one: Acked-by: Lianbo Jiang <[email protected]>
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