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

[lijiang]

在 2021年04月26日 09:37, HAGIO KAZUHITO(萩尾　一仁) 写道:
> 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 at nec.com>
> ---
>  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)) 
> 

Acked-by: Lianbo Jiang <lijiang at redhat.com>