Re: [Crash-utility] [PATCH] Add alternate HZ calculation using write_expire

Linux 4.8 and later kernels that contain kernel commit 9a7f38c42c2b ("cfq-iosched: Convert from jiffies to nanoseconds") changed the definition of cfq_slice_async, and it cannot be used to calculate the HZ value. Add alternate HZ calculation using write_expire, which depends on CONFIG_MQ_IOSCHED_DEADLINE or CONFIG_IOSCHED_DEADLINE. Signed-off-by: Kazuhito Hagio <k-hagio-ab(a)nec.com&gt; --- task.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/task.c b/task.c index ce2b55f430e0..36cf259e5d7b 100644 --- a/task.c +++ b/task.c @@ -432,6 +432,29 @@ task_init(void) "cfq_slice_async exists: setting hz to %d\n", machdep->hz); } + } else if ((symbol_exists("dd_init_queue") && + gdb_set_crash_scope(symbol_value("dd_init_queue"), "dd_init_queue")) || + (symbol_exists("deadline_init_queue") && + gdb_set_crash_scope(symbol_value("deadline_init_queue"), "deadline_init_queue"))) { + char buf[BUFSIZE]; + uint write_expire = 0; + + open_tmpfile(); + sprintf(buf, "printf \"%%d\", write_expire"); + if (gdb_pass_through(buf, pc->tmpfile, GNU_RETURN_ON_ERROR)) { + rewind(pc->tmpfile); + if (fgets(buf, BUFSIZE, pc->tmpfile)) + sscanf(buf, "%d", &write_expire); + } + close_tmpfile(); + + if (write_expire) { + machdep->hz = write_expire / 5; + if (CRASHDEBUG(2)) + fprintf(fp, "write_expire exists: setting hz to %d\n", + machdep->hz); + } + gdb_set_crash_scope(0, NULL); } if (VALID_MEMBER(runqueue_arrays))