On Wed, Sep 03, 2014 at 03:02:36PM +0200, Imre Palik wrote:
> From: "Palik, Imre" <im...@amazon.de>
>
> If the drbd backing device is a new device mapper device (e.g., a
> dm-linear mapping of an existing block device that contains data), the
> counters are initially 0 even though the device contains useful
> data. This causes throttling until something accesses the drbd device
> or the backing device.
>
> The patch disables throttling, as long as only resync is responsible
> for disk activity on a freshly created device.
You are right, the !device->rs_last_events was supposed to be an
indicator of "just started resync, please call once to initialize".
But if curr_events stays 0, which is quite possible given the bursty
nature of the DRBD resync, that will stay 0, and keep throttling.
I'm not sure I like your patch, though.
We may want to properly initialize rs_last_events instead.
I'll think about that...
Lars Ellenberg
> Reported-by: Mikhail Sugakov <msuga...@amazon.de>
> Cc: Matt Wilson <m...@amazon.com>
> Signed-off-by: Imre Palik <im...@amazon.de>
> ---
> drivers/block/drbd/drbd_receiver.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/block/drbd/drbd_receiver.c
> b/drivers/block/drbd/drbd_receiver.c
> index 9342b8d..511d2eb 100644
> --- a/drivers/block/drbd/drbd_receiver.c
> +++ b/drivers/block/drbd/drbd_receiver.c
> @@ -2482,7 +2482,8 @@ bool drbd_rs_c_min_rate_throttle(struct drbd_device
> *device)
> atomic_read(&device->rs_sect_ev);
>
> if (atomic_read(&device->ap_actlog_cnt)
> - || !device->rs_last_events || curr_events - device->rs_last_events
> > 64) {
> + || (curr_events && (!device->rs_last_events
> + || curr_events - device->rs_last_events
> > 64))) {
> unsigned long rs_left;
> int i;
>
> --
> 1.7.9.5
>
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