[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [RFC PATCH] xen-netback: making the bandwidth limiter runtime settable
On 03/17/15 12:17, Wei Liu wrote: > On Fri, Mar 13, 2015 at 01:51:05PM +0100, Imre Palik wrote: >> From: "Palik, Imre" <imrep@xxxxxxxxx> >> >> With the current netback, the bandwidth limiter's parameters are only >> settable during vif setup time. This patch register a watch on them, and >> thus makes them runtime changeable. >> >> When the watch fires, the timer is reset. The timer's mutex is used for >> fencing the change. >> > > I think this is a valid idea. Just that this commit message is not > complete. It doesn't describe everything this patch does. > >> Cc: Anthony Liguori <aliguori@xxxxxxxxxx> >> Signed-off-by: Imre Palik <imrep@xxxxxxxxx> >> --- > [...] >> queue->rx_queue_max = XENVIF_RX_QUEUE_BYTES; >> diff --git a/drivers/net/xen-netback/netback.c >> b/drivers/net/xen-netback/netback.c >> index cab9f52..bcc1880 100644 >> --- a/drivers/net/xen-netback/netback.c >> +++ b/drivers/net/xen-netback/netback.c >> @@ -641,7 +641,7 @@ static void tx_add_credit(struct xenvif_queue *queue) >> queue->remaining_credit = min(max_credit, max_burst); >> } >> >> -static void tx_credit_callback(unsigned long data) >> +void xenvif_tx_credit_callback(unsigned long data) > > Please keep this function static. The trouble with that, is that now I am initialising credit_timeout.function in drivers/net/xen-netback/interface.c . The reason for the change is that mod_timer_pending() hits a BUG() if the timeout function is not initialised. > > And say in the commit message you change tx_credit_callback to a better > name. > >> { >> struct xenvif_queue *queue = (struct xenvif_queue *)data; >> tx_add_credit(queue); >> @@ -1170,7 +1170,7 @@ static bool tx_credit_exceeded(struct xenvif_queue >> *queue, unsigned size) >> queue->credit_timeout.data = >> (unsigned long)queue; >> queue->credit_timeout.function = >> - tx_credit_callback; >> + xenvif_tx_credit_callback; >> mod_timer(&queue->credit_timeout, >> next_credit); > [...] >> @@ -594,13 +597,9 @@ static void xen_net_read_rate(struct xenbus_device *dev, >> unsigned long b, u; >> char *ratestr; >> >> - /* Default to unlimited bandwidth. */ >> - *bytes = ~0UL; >> - *usec = 0; >> - >> ratestr = xenbus_read(XBT_NIL, dev->nodename, "rate", NULL); >> if (IS_ERR(ratestr)) >> - return; >> + goto reset; >> >> s = ratestr; >> b = simple_strtoul(s, &e, 10); >> @@ -612,15 +611,21 @@ static void xen_net_read_rate(struct xenbus_device >> *dev, >> if ((s == e) || (*e != '\0')) >> goto fail; >> >> + kfree(ratestr); >> + >> *bytes = b; >> *usec = u; >> >> - kfree(ratestr); >> return; >> >> - fail: >> +fail: >> pr_warn("Failed to parse network rate limit. Traffic unlimited.\n"); >> kfree(ratestr); >> + >> +reset: >> + /* Default to unlimited bandwidth. */ >> + *bytes = ~0UL; >> + *usec = 0; >> } >> > > Any reason you modify this function? It is still doing the exact same > thing, right? These changes made sense before the channel support, but not anymore. I will roll them back. > >> static int xen_net_read_mac(struct xenbus_device *dev, u8 mac[]) >> @@ -645,6 +650,59 @@ static int xen_net_read_mac(struct xenbus_device *dev, >> u8 mac[]) >> return 0; >> } >> >> +static void xen_net_rate_changed(struct xenbus_watch *watch, >> + const char **vec, unsigned int len) >> +{ >> + struct xenvif *vif = container_of(watch, struct xenvif, credit_watch); >> + struct xenbus_device *dev = xenvif_to_xenbus_device(vif); >> + unsigned long credit_bytes; >> + unsigned long credit_usec; >> + unsigned int queue_index; >> + >> + xen_net_read_rate(dev, &credit_bytes, &credit_usec); >> + for (queue_index = 0; queue_index < vif->num_queues; queue_index++) { >> + struct xenvif_queue *queue = &vif->queues[queue_index]; >> + >> + queue->credit_bytes = credit_bytes; >> + queue->credit_usec = credit_usec; >> + if (!mod_timer_pending(&queue->credit_timeout, jiffies) && >> + queue->remaining_credit > queue->credit_bytes) { >> + queue->remaining_credit = queue->credit_bytes; >> + } >> + } >> +} >> + >> +static int xen_register_watchers(struct xenbus_device *dev, struct xenvif >> *vif) >> +{ >> + int err = 0; >> + char *node; >> + unsigned maxlen = strlen(dev->nodename) + sizeof("/rate"); >> + >> + node = kmalloc(maxlen, GFP_KERNEL); >> + if (!node) >> + return -ENOMEM; >> + sprintf(node, "%s/rate", dev->nodename); > > Please use snprintf. (Though I can see using sprintf is fine here but I > want the code to be a bit future proof.) > >> + vif->credit_watch.node = node; >> + vif->credit_watch.callback = xen_net_rate_changed; >> + err = register_xenbus_watch(&vif->credit_watch); >> + if (err) { >> + pr_err("Failed to set watcher %s\n", vif->credit_watch.node); >> + kfree(node); >> + vif->credit_watch.node = 0; >> + vif->credit_watch.callback = 0; > > Please use NULL here. > > Wei. > _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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