From: Paolo Bonzini <pbonzini@redhat.com>
To: quintela@redhat.com, Jitendra Kolhe <jitendra.kolhe@hpe.com>
Cc: qemu-devel@nongnu.org, kwolf@redhat.com,
peter.maydell@linaro.org, armbru@redhat.com,
renganathan.meenakshisundaram@hpe.com,
mohan_parthasarathy@hpe.com
Subject: Re: [Qemu-devel] [PATCH RFC] mem-prealloc: Reduce large guest start-up and migration time.
Date: Fri, 27 Jan 2017 14:06:40 +0100 [thread overview]
Message-ID: <ad61f8a7-e18a-3a20-92d9-8cf11d4a873e@redhat.com> (raw)
In-Reply-To: <87mvec3bqp.fsf@emacs.mitica>
On 27/01/2017 13:53, Juan Quintela wrote:
>> +static void *do_touch_pages(void *arg)
>> +{
>> + PageRange *range = (PageRange *)arg;
>> + char *start_addr = range->addr;
>> + uint64_t numpages = range->numpages;
>> + uint64_t hpagesize = range->hpagesize;
>> + uint64_t i = 0;
>> +
>> + for (i = 0; i < numpages; i++) {
>> + memset(start_addr + (hpagesize * i), 0, 1);
>
> I would use the range->addr and similar here directly, but it is just a
> question of taste.
>
>> - /* MAP_POPULATE silently ignores failures */
>> - for (i = 0; i < numpages; i++) {
>> - memset(area + (hpagesize * i), 0, 1);
>> + /* touch pages simultaneously for memory >= 64G */
>> + if (memory < (1ULL << 36)) {
>
> 64GB guest already took quite a bit of time, I think I would put it
> always as min(num_vcpus, 16). So, we always execute the multiple theard
> codepath?
I too would like some kind of heuristic to choose the number of threads.
Juan's suggested usage of the VCPUs (smp_cpus) is a good one.
Paolo
next prev parent reply other threads:[~2017-01-27 13:06 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-05 7:24 [Qemu-devel] [PATCH RFC] mem-prealloc: Reduce large guest start-up and migration time Jitendra Kolhe
2017-01-27 12:53 ` Juan Quintela
2017-01-27 13:06 ` Paolo Bonzini [this message]
2017-01-30 8:19 ` Jitendra Kolhe
2017-01-27 13:03 ` Dr. David Alan Gilbert
2017-01-30 8:32 ` Jitendra Kolhe
2017-02-07 7:44 ` Jitendra Kolhe
2017-01-27 13:26 ` Daniel P. Berrange
2017-02-02 9:35 ` Jitendra Kolhe
2017-02-03 18:59 ` Paolo Bonzini
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