diff options
| author | Maciej Żenczykowski <maze@google.com> | 2021-06-08 01:54:38 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-06-09 10:34:18 +0200 |
| commit | 1958ff5ad2d4908b44a72bcf564dfe67c981e7fe (patch) | |
| tree | 7f006b805b421effb2193d265de444969a103e8b | |
| parent | 3370139745853f7826895293e8ac3aec1430508e (diff) | |
| download | linux-1958ff5ad2d4908b44a72bcf564dfe67c981e7fe.tar.bz2 | |
usb: f_ncm: only first packet of aggregate needs to start timer
The reasoning for this change is that if we already had
a packet pending, then we also already had a pending timer,
and as such there is no need to reschedule it.
This also prevents packets getting delayed 60 ms worst case
under a tiny packet every 290us transmit load, by keeping the
timeout always relative to the first queued up packet.
(300us delay * 16KB max aggregation / 80 byte packet =~ 60 ms)
As such the first packet is now at most delayed by 300us.
Under low transmit load, this will simply result in us sending
a shorter aggregate, as originally intended.
This patch has the benefit of greatly reducing (by ~10 factor
with 1500 byte frames aggregated into 16 kiB) the number of
(potentially pretty costly) updates to the hrtimer.
Cc: Brooke Basile <brookebasile@gmail.com>
Cc: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Cc: Felipe Balbi <balbi@kernel.org>
Cc: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Link: https://lore.kernel.org/r/20210608085438.813960-1-zenczykowski@gmail.com
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/usb/gadget/function/f_ncm.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/drivers/usb/gadget/function/f_ncm.c b/drivers/usb/gadget/function/f_ncm.c index 0d23c6c11a13..855127249f24 100644 --- a/drivers/usb/gadget/function/f_ncm.c +++ b/drivers/usb/gadget/function/f_ncm.c @@ -1101,11 +1101,11 @@ static struct sk_buff *ncm_wrap_ntb(struct gether *port, ncm->ndp_dgram_count = 1; /* Note: we skip opts->next_ndp_index */ - } - /* Delay the timer. */ - hrtimer_start(&ncm->task_timer, TX_TIMEOUT_NSECS, - HRTIMER_MODE_REL_SOFT); + /* Start the timer. */ + hrtimer_start(&ncm->task_timer, TX_TIMEOUT_NSECS, + HRTIMER_MODE_REL_SOFT); + } /* Add the datagram position entries */ ntb_ndp = skb_put_zero(ncm->skb_tx_ndp, dgram_idx_len); |