Date: Tue, 27 Oct 2015 13:58:10 +0200 From: Konstantin Belousov <kostikbel@gmail.com> To: Andriy Gapon <avg@FreeBSD.org> Cc: freebsd-hackers <freebsd-hackers@FreeBSD.org>, Poul-Henning Kamp <phk@phk.freebsd.dk>, Jung-uk Kim <jkim@FreeBSD.org> Subject: Re: instability of timekeeping Message-ID: <20151027115810.GU2257@kib.kiev.ua> In-Reply-To: <562F3E2F.2010100@FreeBSD.org> References: <56261398.60102@FreeBSD.org> <56261FE6.90302@FreeBSD.org> <56274FFC.2000608@FreeBSD.org> <20151021184850.GX2257@kib.kiev.ua> <562F3E2F.2010100@FreeBSD.org>
index | next in thread | previous in thread | raw e-mail
On Tue, Oct 27, 2015 at 11:04:47AM +0200, Andriy Gapon wrote: > And now another observation. I have C1E option enabled in BIOS. It > means that if all cores enter C1 state, then the whole processor > is magically placed into a deep C-state (C3, I think). LAPIC timer > on this CPU model does not run in the deep C-state. So, I had to > disable C1E option to test the LAPIC timer in a useful way. But > before actually testing it I first tried to reproduce the problem. As > you might have already guessed the problem is gone with that option > disabled. Scratching my head to understand the implications of this > observation. Most obvious explanation would be that the latency of wakeup is very large. What is the HPET frequency when the jitter occur ?help
Want to link to this message? Use this
URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20151027115810.GU2257>