On 21/11/2015 00:05, Ming Lin wrote:
> [ 1.752129] Freeing unused kernel memory: 420K (ffff880001b97000 - ffff880001c00000)
> [ 1.986573] clocksource: tsc: mask: 0xffffffffffffffff max_cycles: 0x30e5c9bbf83, max_idle_ns: 440795378954 ns
> [ 1.988187] clocksource: Switched to clocksource tsc
> [ 3.235423] clocksource: timekeeping watchdog: Marking clocksource 'tsc' as unstable because the skew is too large:
> [ 3.358713] clocksource: 'refined-jiffies' wd_now: fffeddf3 wd_last: fffedd76 mask: ffffffff
> [ 3.410013] clocksource: 'tsc' cs_now: 3c121d4ec cs_last: 340888eb7 mask: ffffffffffffffff
> [ 3.450026] clocksource: Switched to clocksource refined-jiffies
> [ 7.696769] Adding 392188k swap on /dev/vda5. Priority:-1 extents:1 across:392188k
> [ 7.902174] EXT4-fs (vda1): re-mounted. Opts: (null)
> [ 8.734178] EXT4-fs (vda1): re-mounted. Opts: errors=remount-ro
>
> Then it doesn't response input for almost 1 minute.
> Without this patch, kernel loads quickly.
Interesting. I guess there's time to debug it, since QEMU 2.6 is still
a few months away. In the meanwhile we can apply your patch as is,
apart from disabling the "if (new_head >= cq->size)" and the similar
one for "if (new_ tail >= sq->size".
But, I have a possible culprit. In your nvme_cq_notifier you are not doing the
equivalent of:
start_sqs = nvme_cq_full(cq) ? 1 : 0;
cq->head = new_head;
if (start_sqs) {
NvmeSQueue *sq;
QTAILQ_FOREACH(sq, &cq->sq_list, entry) {
timer_mod(sq->timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + 500);
}
timer_mod(cq->timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + 500);
}
Instead, you are just calling nvme_post_cqes, which is the equivalent of
timer_mod(cq->timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + 500);
Adding a loop to nvme_cq_notifier, and having it call nvme_process_sq, might
fix the weird 1-minute delay.
Paolo
> void memory_region_add_eventfd(MemoryRegion *mr,
> hwaddr addr,
> unsigned size,
> bool match_data,
> uint64_t data,
> EventNotifier *e)
>
> Could you help to explain what "match_data" and "data" mean?
If match_data is true, the eventfd is only signalled if "data" is being written to memory.
Paolo
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