Re: [PATCH 02/11] migration/hmp: Fix postcopy-blocktime per-vCPU results
On Wed, May 28, 2025 at 03:08:38PM +, Dr. David Alan Gilbert wrote: > * Markus Armbruster ([email protected]) wrote: > > Peter Xu writes: > > > > > Unfortunately, it was never correctly shown.. > > > > > > This is only found when I started to look into making the blocktime > > > feature > > > more useful (so as to avoid using bpftrace, even though I'm not sure which > > > one will be harder to use..). > > > > > > So the old dump would look like this: > > > > > > Postcopy vCPU Blocktime: 0-1,4,10,21,33,46,48,59 > > > > > > Even though there're actually 40 vcpus, and the string will merge same > > > elements and also sort them. > > > > > > To fix it, simply loop over the uint32List manually. Now it looks like: > > > > > > Postcopy vCPU Blocktime (ms): > > >[15, 0, 0, 43, 29, 34, 36, 29, 37, 41, > > > 33, 37, 45, 52, 50, 38, 40, 37, 40, 49, > > > 40, 35, 35, 35, 81, 19, 18, 19, 18, 30, > > > 22, 3, 0, 0, 0, 0, 0, 0, 0, 0] > > > > > > Cc: Dr. David Alan Gilbert > > > Cc: Alexey Perevalov > > > Cc: Markus Armbruster > > > Signed-off-by: Peter Xu > > > --- > > > migration/migration-hmp-cmds.c | 23 ++- > > > 1 file changed, 14 insertions(+), 9 deletions(-) > > > > > > diff --git a/migration/migration-hmp-cmds.c > > > b/migration/migration-hmp-cmds.c > > > index 367ff6037f..3cf890b887 100644 > > > --- a/migration/migration-hmp-cmds.c > > > +++ b/migration/migration-hmp-cmds.c > > > @@ -208,15 +208,20 @@ void hmp_info_migrate(Monitor *mon, const QDict > > > *qdict) > > > } > > > > > > if (info->has_postcopy_vcpu_blocktime) { > > > -Visitor *v; > > > -char *str; > > > -v = string_output_visitor_new(false, &str); > > > -visit_type_uint32List(v, NULL, &info->postcopy_vcpu_blocktime, > > > - &error_abort); > > > -visit_complete(v, &str); > > > -monitor_printf(mon, "Postcopy vCPU Blocktime: %s\n", str); > > > -g_free(str); > > > -visit_free(v); > > > +uint32List *item = info->postcopy_vcpu_blocktime; > > > +int count = 0; > > > + > > > +monitor_printf(mon, "Postcopy vCPU Blocktime (ms): \n ["); > > > + > > > +while (item) { > > > +monitor_printf(mon, "%"PRIu32", ", item->value); > > > +item = item->next; > > > +/* Each line 10 vcpu results, newline if there's more */ > > > > The list can be arbitrarily long? > > One per vCPU, so a small arbitrary. > > > > +if ((++count % 10 == 0) && item) { > > > +monitor_printf(mon, "\n "); > > > +} > > > +} > > > +monitor_printf(mon, "\b\b]\n"); > > > > Uh, backspace? > > Agreed! Agreed on.. using backspace? :) > > Dave > > > I usually do something like > > > > sep = ""; > > for (...) { > > printf("%s...", sep, ...); > > sep = ", " > > } > > > > To add line breaks, I'd use something like > > > > sep = ... ? ", " : ",\n"; Thanks for the suggestion! Definitely better.. I'll squash below into this patch when repost, comments on top always welcomed. diff --git a/migration/migration-hmp-cmds.c b/migration/migration-hmp-cmds.c index 3cf890b887..6c36e202a0 100644 --- a/migration/migration-hmp-cmds.c +++ b/migration/migration-hmp-cmds.c @@ -209,19 +209,18 @@ void hmp_info_migrate(Monitor *mon, const QDict *qdict) if (info->has_postcopy_vcpu_blocktime) { uint32List *item = info->postcopy_vcpu_blocktime; +const char *sep = ""; int count = 0; monitor_printf(mon, "Postcopy vCPU Blocktime (ms): \n ["); while (item) { -monitor_printf(mon, "%"PRIu32", ", item->value); +monitor_printf(mon, "%s%"PRIu32, sep, item->value); item = item->next; /* Each line 10 vcpu results, newline if there's more */ -if ((++count % 10 == 0) && item) { -monitor_printf(mon, "\n "); -} +sep = ((++count % 10 == 0) && item) ? ",\n " : ", "; } -monitor_printf(mon, "\b\b]\n"); +monitor_printf(mon, "]\n"); } -- Peter Xu
Re: [PATCH 02/11] migration/hmp: Fix postcopy-blocktime per-vCPU results
* Markus Armbruster ([email protected]) wrote: > Peter Xu writes: > > > Unfortunately, it was never correctly shown.. > > > > This is only found when I started to look into making the blocktime feature > > more useful (so as to avoid using bpftrace, even though I'm not sure which > > one will be harder to use..). > > > > So the old dump would look like this: > > > > Postcopy vCPU Blocktime: 0-1,4,10,21,33,46,48,59 > > > > Even though there're actually 40 vcpus, and the string will merge same > > elements and also sort them. > > > > To fix it, simply loop over the uint32List manually. Now it looks like: > > > > Postcopy vCPU Blocktime (ms): > >[15, 0, 0, 43, 29, 34, 36, 29, 37, 41, > > 33, 37, 45, 52, 50, 38, 40, 37, 40, 49, > > 40, 35, 35, 35, 81, 19, 18, 19, 18, 30, > > 22, 3, 0, 0, 0, 0, 0, 0, 0, 0] > > > > Cc: Dr. David Alan Gilbert > > Cc: Alexey Perevalov > > Cc: Markus Armbruster > > Signed-off-by: Peter Xu > > --- > > migration/migration-hmp-cmds.c | 23 ++- > > 1 file changed, 14 insertions(+), 9 deletions(-) > > > > diff --git a/migration/migration-hmp-cmds.c b/migration/migration-hmp-cmds.c > > index 367ff6037f..3cf890b887 100644 > > --- a/migration/migration-hmp-cmds.c > > +++ b/migration/migration-hmp-cmds.c > > @@ -208,15 +208,20 @@ void hmp_info_migrate(Monitor *mon, const QDict > > *qdict) > > } > > > > if (info->has_postcopy_vcpu_blocktime) { > > -Visitor *v; > > -char *str; > > -v = string_output_visitor_new(false, &str); > > -visit_type_uint32List(v, NULL, &info->postcopy_vcpu_blocktime, > > - &error_abort); > > -visit_complete(v, &str); > > -monitor_printf(mon, "Postcopy vCPU Blocktime: %s\n", str); > > -g_free(str); > > -visit_free(v); > > +uint32List *item = info->postcopy_vcpu_blocktime; > > +int count = 0; > > + > > +monitor_printf(mon, "Postcopy vCPU Blocktime (ms): \n ["); > > + > > +while (item) { > > +monitor_printf(mon, "%"PRIu32", ", item->value); > > +item = item->next; > > +/* Each line 10 vcpu results, newline if there's more */ > > The list can be arbitrarily long? One per vCPU, so a small arbitrary. > > +if ((++count % 10 == 0) && item) { > > +monitor_printf(mon, "\n "); > > +} > > +} > > +monitor_printf(mon, "\b\b]\n"); > > Uh, backspace? Agreed! Dave > I usually do something like > > sep = ""; > for (...) { > printf("%s...", sep, ...); > sep = ", " > } > > To add line breaks, I'd use something like > > sep = ... ? ", " : ",\n"; > > > } > > > > out: > > The less the string visitors are used, the happier I am. > -- -Open up your eyes, open up your mind, open up your code --- / Dr. David Alan Gilbert| Running GNU/Linux | Happy \ \dave @ treblig.org | | In Hex / \ _|_ http://www.treblig.org |___/
Re: [PATCH 02/11] migration/hmp: Fix postcopy-blocktime per-vCPU results
Peter Xu writes:
> Unfortunately, it was never correctly shown..
>
> This is only found when I started to look into making the blocktime feature
> more useful (so as to avoid using bpftrace, even though I'm not sure which
> one will be harder to use..).
>
> So the old dump would look like this:
>
> Postcopy vCPU Blocktime: 0-1,4,10,21,33,46,48,59
>
> Even though there're actually 40 vcpus, and the string will merge same
> elements and also sort them.
>
> To fix it, simply loop over the uint32List manually. Now it looks like:
>
> Postcopy vCPU Blocktime (ms):
>[15, 0, 0, 43, 29, 34, 36, 29, 37, 41,
> 33, 37, 45, 52, 50, 38, 40, 37, 40, 49,
> 40, 35, 35, 35, 81, 19, 18, 19, 18, 30,
> 22, 3, 0, 0, 0, 0, 0, 0, 0, 0]
>
> Cc: Dr. David Alan Gilbert
> Cc: Alexey Perevalov
> Cc: Markus Armbruster
> Signed-off-by: Peter Xu
> ---
> migration/migration-hmp-cmds.c | 23 ++-
> 1 file changed, 14 insertions(+), 9 deletions(-)
>
> diff --git a/migration/migration-hmp-cmds.c b/migration/migration-hmp-cmds.c
> index 367ff6037f..3cf890b887 100644
> --- a/migration/migration-hmp-cmds.c
> +++ b/migration/migration-hmp-cmds.c
> @@ -208,15 +208,20 @@ void hmp_info_migrate(Monitor *mon, const QDict *qdict)
> }
>
> if (info->has_postcopy_vcpu_blocktime) {
> -Visitor *v;
> -char *str;
> -v = string_output_visitor_new(false, &str);
> -visit_type_uint32List(v, NULL, &info->postcopy_vcpu_blocktime,
> - &error_abort);
> -visit_complete(v, &str);
> -monitor_printf(mon, "Postcopy vCPU Blocktime: %s\n", str);
> -g_free(str);
> -visit_free(v);
> +uint32List *item = info->postcopy_vcpu_blocktime;
> +int count = 0;
> +
> +monitor_printf(mon, "Postcopy vCPU Blocktime (ms): \n [");
> +
> +while (item) {
> +monitor_printf(mon, "%"PRIu32", ", item->value);
> +item = item->next;
> +/* Each line 10 vcpu results, newline if there's more */
The list can be arbitrarily long?
> +if ((++count % 10 == 0) && item) {
> +monitor_printf(mon, "\n ");
> +}
> +}
> +monitor_printf(mon, "\b\b]\n");
Uh, backspace?
I usually do something like
sep = "";
for (...) {
printf("%s...", sep, ...);
sep = ", "
}
To add line breaks, I'd use something like
sep = ... ? ", " : ",\n";
> }
>
> out:
The less the string visitors are used, the happier I am.
