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From: | Richard Henderson |
Subject: | Re: [PATCH] virtio-blk: Convert QEMUBH callback to "bitops.h" API |
Date: | Thu, 6 May 2021 11:22:14 -0700 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 |
On 5/6/21 8:54 AM, Philippe Mathieu-Daudé wrote:
static void notify_guest_bh(void *opaque) { VirtIOBlockDataPlane *s = opaque; - unsigned nvqs = s->conf->num_queues; - unsigned long bitmap[BITS_TO_LONGS(nvqs)]; - unsigned j;- memcpy(bitmap, s->batch_notify_vqs, sizeof(bitmap));- memset(s->batch_notify_vqs, 0, sizeof(bitmap)); - - for (j = 0; j < nvqs; j += BITS_PER_LONG) { - unsigned long bits = bitmap[j / BITS_PER_LONG]; - - while (bits != 0) { - unsigned i = j + ctzl(bits); + for (unsigned i = 0; i < s->conf->num_queues; i++) {
Is this bitmap dense enough that you want to iterate by index, or is it sparse enough to iterate via find_first_bit/find_next_bit?
In either case, leave the copy of s->conf->num_queues to a local variable. r~
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