On Tue, Jan 07, 2025 at 03:04:40PM -0800, Yury Norov wrote:
On Tue, Jan 07, 2025 at 02:43:01PM -0800, Yury Norov wrote:
quoted
On Tue, Jan 07, 2025 at 04:37:17PM -0600, Nick Child wrote:
quoted
On Sat, Dec 28, 2024 at 10:49:35AM -0800, Yury Norov wrote:
quoted
A loop based on cpumask_next_wrap() opencodes the dedicated macro
for_each_online_cpu_wrap(). Using the macro allows to avoid setting
bits affinity mask more than once when stride >= num_online_cpus.
This also helps to drop cpumask handling code in the caller function.
Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
drivers/net/ethernet/ibm/ibmvnic.c | 17 ++++++++++-------
1 file changed, 10 insertions(+), 7 deletions(-)
diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
index e95ae0d39948..4cfd90fb206b 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c
@@ -234,11 +234,16 @@ static int ibmvnic_set_queue_affinity(struct ibmvnic_sub_crq_queue *queue,
(*stragglers)--;
}
/* atomic write is safer than writing bit by bit directly */
- for (i = 0; i < stride; i++) {
- cpumask_set_cpu(*cpu, mask);
- *cpu = cpumask_next_wrap(*cpu, cpu_online_mask,
- nr_cpu_ids, false);
+ for_each_online_cpu_wrap(i, *cpu) {
+ if (!stride--)
+ break;
+ cpumask_set_cpu(i, mask);
}
+
+ /* For the next queue we start from the first unused CPU in this queue */
+ if (i < nr_cpu_ids)
+ *cpu = i + 1;
+
This should read '*cpu = i'. Since the loop breaks after incrementing i.
Thanks!
cpumask_next_wrap() makes '+ 1' for you. The for_each_cpu_wrap() starts
exactly where you point. So, this '+1' needs to be explicit now.
Does that make sense?
Ah, I think I see what you mean. It should be like this, right?
for_each_online_cpu_wrap(i, *cpu) {
if (!stride--) {
*cpu = i + 1;
break;
}
cpumask_set_cpu(i, mask);
}
Not quite, for_each_online_cpu_wrap will increment i to point to the
next online cpu, then enter the body of the loop. When we break (beacuse
stride is zero), we exit the loop early before i is added to any mask, i
is the next unassigned online cpu.
I tested this to make sure, we see unused cpus (#7, #23) with the patch as is:
IRQ : 256 -> ibmvnic-30000003-tx0
/proc/irq/256/smp_affinity_list:0-6
IRQ : 257 -> ibmvnic-30000003-tx1
/proc/irq/257/smp_affinity_list:16-22
IRQ : 258 -> ibmvnic-30000003-rx0
/proc/irq/258/smp_affinity_list:8-14
IRQ : 259 -> ibmvnic-30000003-rx1
/proc/irq/259/smp_affinity_list:24-30