Thread (48 messages) 48 messages, 3 authors, 2021-01-10

RE: [EXT] Re: [PATCH RFC net-next 11/19] net: mvpp2: add flow control RXQ and BM pool config callbacks

From: Stefan Chulski <hidden>
Date: 2021-01-10 18:25:47
Also in: lkml

quoted
+/* Routine calculate single queue shares address space */ static int
+mvpp22_calc_shared_addr_space(struct mvpp2_port *port) {
+	/* If number of CPU's greater than number of threads, return last
+	 * address space
+	 */
+	if (num_active_cpus() >= MVPP2_MAX_THREADS)
+		return MVPP2_MAX_THREADS - 1;
+
+	return num_active_cpus();
Firstly - this can be written as:

	return min(num_active_cpus(), MVPP2_MAX_THREADS - 1);
OK.
Secondly - what if the number of active CPUs change, for example due to
hotplug activity. What if we boot with maxcpus=1 and then bring the other
CPUs online after networking has been started? The number of active CPUs is
dynamically managed via the scheduler as CPUs are brought online or offline.
quoted
+/* Routine enable flow control for RXQs conditon */ void
+mvpp2_rxq_enable_fc(struct mvpp2_port *port)
...
quoted
+/* Routine disable flow control for RXQs conditon */ void
+mvpp2_rxq_disable_fc(struct mvpp2_port *port)
Nothing seems to call these in this patch, so on its own, it's not obvious how
these are being called, and therefore what remedy to suggest for
num_active_cpus().
I don't think that current driver support CPU hotplug, anyway I can remove  num_active_cpus
and just use shared RX IRQ ID.

Thanks.
. 
Keyboard shortcuts
hback out one level
jnext message in thread
kprevious message in thread
ldrill in
Escclose help / fold thread tree
?toggle this help