diff options
| author | Costa Shulyupin <costa.shul@redhat.com> | 2024-09-26 12:26:22 +0300 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2024-11-14 22:43:52 +1100 |
| commit | 6da1cab4f5f8eb778fd61f0eb6ca5b0a011dd44d (patch) | |
| tree | fad97c75f7f3b2e53f6a363b4b6eefd13aef38f4 | |
| parent | 7ca93aa9204b706e4afcd4fae0dc8798500598d5 (diff) | |
powerpc/xive: Use cpumask_intersects()
Replace `cpumask_any_and(a, b) >= nr_cpu_ids`
with the more readable `!cpumask_intersects(a, b)`.
Comparison between cpumask_any_and() and cpumask_intersects()
The cpumask_any_and() function expands using FIND_FIRST_BIT(),
resulting in a loop that iterates through each bit of the bitmask:
for (idx = 0; idx * BITS_PER_LONG < sz; idx++) {
val = (FETCH);
if (val) {
sz = min(idx * BITS_PER_LONG + __ffs(MUNGE(val)), sz);
break;
}
}
The cpumask_intersects() function expands using __bitmap_intersects(),
resulting in that the first loop iterates through each long word of the bitmask,
and the second through each bit within a long word:
unsigned int k, lim = bits/BITS_PER_LONG;
for (k = 0; k < lim; ++k)
if (bitmap1[k] & bitmap2[k])
return true;
if (bits % BITS_PER_LONG)
if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
return true;
Conclusion: cpumask_intersects() is at least as efficient as cpumask_any_and(),
if not more so, as it typically performs fewer loops and comparisons.
Signed-off-by: Costa Shulyupin <costa.shul@redhat.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://patch.msgid.link/20240926092623.399577-2-costa.shul@redhat.com
| -rw-r--r-- | arch/powerpc/sysdev/xive/common.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/powerpc/sysdev/xive/common.c b/arch/powerpc/sysdev/xive/common.c index fa01818c1972..a6c388bdf5d0 100644 --- a/arch/powerpc/sysdev/xive/common.c +++ b/arch/powerpc/sysdev/xive/common.c @@ -726,7 +726,7 @@ static int xive_irq_set_affinity(struct irq_data *d, pr_debug("%s: irq %d/0x%x\n", __func__, d->irq, hw_irq); /* Is this valid ? */ - if (cpumask_any_and(cpumask, cpu_online_mask) >= nr_cpu_ids) + if (!cpumask_intersects(cpumask, cpu_online_mask)) return -EINVAL; /* |