[LTP] [PATCH v4] mm: rewrite mtest01 with new API
Wed Mar 13 13:52:47 CET 2019
On Wed, Mar 13, 2019 at 7:48 PM Jan Stancek <email@example.com> wrote:
> From: Li Wang <firstname.lastname@example.org>
> Test issue:
> mtest01 start many children to alloc chunck of memory and do write
> page(with -w option), but occasionally some children were killed by
> oom-killer and exit with SIGCHLD signal sending. After the parent
> reciving this SIGCHLD signal it will report FAIL as a test result.
> It seems not a real kernel bug if something just like that, it's
> trying to use 80% of memory and swap. Once it uses most of memory,
> system starts swapping, but the test is likely consuming memory at
> greater rate than kswapd can provide, which eventually triggers OOM.
> ---- FAIL LOG ----
> mtest01 0 TINFO : Total memory already used on system = 1027392
> mtest01 0 TINFO : Total memory used needed to reach maximum =
> 12715520 kbytes
> mtest01 0 TINFO : Filling up 80% of ram which is 11688128 kbytes
> mtest01 1 TFAIL : mtest01.c:314: child process exited
> Rewrite changes:
> To make mtest01 more easier to understand, I just rewrite it into
> LTP new API and make a little changes in children behavior.
> * decrease the pressure to 80% of free memory for testing
> * drop the signal SIGCHLD action becasue new API help to
> * make child pause itself after finishing their memory
> * parent sends SIGCONT to make children continue and exit
> * use TST_PROCESS_STATE_WAIT to wait child changes to 'T' state
> * involve ALLOC_THRESHOLD to rework same code in defines
> * to make mtest01 support running with -i N > 1
> Signed-off-by: Li Wang <email@example.com>
> Signed-off-by: Jan Stancek <firstname.lastname@example.org>
> I'm posting v4 because I'm proposing also couple other small changes.
> Changes in v4:
> - fix -b parameter, it was ignored, because maxpercent is always non-zero
> Now, if -b is set, then maxpercent is ignored.
> - remove casts to unsigned long long, use literal with ULL suffix
> - pid_count renamed to children_done, because pid_count vs. pid_cntr was
> - original_maxbytes dropped, instead alloc_maxbytes remains unchanged in
> - do_write_page renamed to do_write_mem, since we write more than single
> - do_write_mem loop now increases offset by page size to make it slightly
> - bytecount initialized to 0 in child_loop_alloc()
> - info messages expanded to show some timestamp (remaining time)
> - PASS/FAIL messages for do_write=0 and do_write=1 consolidated to single
> - child creation loop in mem_test() tweaked:
> - child_loop_alloc() called directly from loop
> - pid_cntr incremented and used as index to pid_list array, 'i' variable
> not used
> - while condition "((pid != 0)" removed, it's always true
> - sleep reduced to 100ms
> - "while (pid_list[i] > 0)" replaced with for loop, since we know exactly
> how many
> children we spawned. memset in setup dropped.
I'm OK with these improvements, patch v4 looks quite good to me:).
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