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Re: [PATCH v3 4/4] xen/console: reduce number of printouts in __printk_ratelimit()
- To: dmukhin@xxxxxxxx
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Thu, 16 Jul 2026 17:49:35 +0200
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- Cc: andrew.cooper3@xxxxxxxxxx, anthony.perard@xxxxxxxxxx, julien@xxxxxxx, michal.orzel@xxxxxxx, roger.pau@xxxxxxxxxx, sstabellini@xxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxxx
- Delivery-date: Thu, 16 Jul 2026 15:49:44 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 15.07.2026 22:19, dmukhin@xxxxxxxx wrote:
> From: Denis Mukhin <dmukhin@xxxxxxxx>
>
> Fold several __putstr() calls into one around notification of how many
> messages have been rate-limited.
>
> Not a functional change.
>
> Signed-off-by: Denis Mukhin <dmukhin@xxxxxxxx>
Hmm, the upsides and downsides aren't being discussed at all. You're ...
> --- a/xen/drivers/char/console.c
> +++ b/xen/drivers/char/console.c
> @@ -1303,15 +1303,15 @@ bool __printk_ratelimit(unsigned int ratelimit_ms,
> spin_unlock(&ratelimit_lock);
> if ( lost )
> {
> - char lost_str[10];
> + char msg[64];
> +
> + snprintf(msg, sizeof(msg),
> + "printk: %u messages suppressed\n", lost);
>
> - snprintf(lost_str, sizeof(lost_str), "%u", lost);
> /* console_lock may already be acquired by printk(). */
> rspin_lock(&console_lock);
> printk_start_of_line(CONSOLE_PREFIX);
> - __putstr("printk: ");
> - __putstr(lost_str);
> - __putstr(" messages suppressed.\n");
> + __putstr(msg);
> rspin_unlock(&console_lock);
> }
> local_irq_restore(flags);
... trading slightly smaller code size + slightly better performance for
slightly bigger stack utilization. It's not entirely obvious that this is
a good deal.
Jan
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