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Re: [PATCH] x86/xen/time: Reduce Xen timer tick
- To: Frediano Ziglio <frediano.ziglio@xxxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Mon, 17 Jun 2024 16:22:21 +0200
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- Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>, x86@xxxxxxxxxx, Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>, Borislav Petkov <bp@xxxxxxxxx>, Ingo Molnar <mingo@xxxxxxxxxx>, Thomas Gleixner <tglx@xxxxxxxxxxxxx>, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>, Juergen Gross <jgross@xxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx
- Delivery-date: Mon, 17 Jun 2024 14:22:32 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 17.06.2024 16:13, Frediano Ziglio wrote:
> Current timer tick is causing some deadline to fail.
> The current high value constant was probably due to an old
> bug in the Xen timer implementation causing errors if the
> deadline was in the future.
> This was fixed in Xen commit:
> 19c6cbd90965 xen/vcpu: ignore VCPU_SSHOTTMR_future
And then newer kernels are no longer reliably usable on Xen older than
this?
> --- a/arch/x86/xen/time.c
> +++ b/arch/x86/xen/time.c
> @@ -30,7 +30,7 @@
> #include "xen-ops.h"
>
> /* Minimum amount of time until next clock event fires */
> -#define TIMER_SLOP 100000
> +#define TIMER_SLOP 1000
It may be just the lack of knowledge of mine towards noadays's Linux'es
time handling, but the change of a value with this name and thus
commented doesn't directly relate to "timer tick" rate. Could you maybe
help me see the connection?
Jan
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