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Message-ID: References: <29775afa-e17b-4c44-a2a8-4ef4bc7cdf0f@suse.com> <88c65ec7-b7f7-4d8b-a453-d707440b43cb@suse.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="F629bKJhvAiDwbl3" Content-Disposition: inline In-Reply-To: X-purgate-ID: tlsNG-d62444/1775489405-BC766185-E61D7C9F/0/0 X-purgate-type: clean X-purgate-size: 3042 --F629bKJhvAiDwbl3 Content-Type: text/plain; protected-headers=v1; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Date: Mon, 6 Apr 2026 17:29:58 +0200 From: Marek =?utf-8?Q?Marczykowski-G=C3=B3recki?= To: Jan Beulich Cc: xen-devel , =?utf-8?B?SsO8cmdlbiBHcm/Dnw==?= , Roger Pau =?utf-8?B?TW9ubsOp?= Subject: Re: Slow (higher scheduling latency?) system after S3 - regression 4.17 -> 4.19 ? On Fri, Apr 03, 2026 at 03:55:07PM +0200, Marek Marczykowski-G=C3=B3recki w= rote: > On Thu, Apr 02, 2026 at 03:02:15PM +0200, Marek Marczykowski-G=C3=B3recki= wrote: > > On Fri, Mar 27, 2026 at 01:47:55PM +0100, Marek Marczykowski-G=C3=B3rec= ki wrote: > > > Some further observation, this time regarding timers: > >=20 > > In the meantime Roger suggested it might be about C-states. So, I just > > tried booting with max_cstate=3D0. I got this: >=20 > We had a design session on this issue, and managed to find (thanks Roger!) > that adding: >=20 > tsc_mode=3D'always_emulate' >=20 > to the domU config fixes the issue. Now, the question is how to fix it > properly... I also did another test with NTP inside domU (after host S3): $ ntpdate -q pool.ntp.org 2026-04-06 00:07:01.559218 (+0200) -0.216281 +/- 0.012486 pool.ntp.org 141.= 144.241.16 s2 no-leap $ ntpdate -q pool.ntp.org 2026-04-06 00:57:40.852612 (+0200) -0.255782 +/- 0.013022 pool.ntp.org 185.= 252.140.125 s2 no-leap $ ntpdate -q pool.ntp.org 2026-04-06 13:07:57.647126 (+0200) -0.791802 +/- 0.056578 pool.ntp.org 185.= 248.188.98 s1 no-leap $ ntpdate -q pool.ntp.org 2026-04-06 13:08:01.844118 (+0200) -0.832599 +/- 0.012563 pool.ntp.org 185.= 248.188.98 s1 no-leap $ ntpdate -q 141.144.241.16 2026-04-06 13:08:47.835271 (+0200) -0.819725 +/- 0.028655 141.144.241.16 s2= no-leap $ ntpdate -q 141.144.241.16 2026-04-06 13:08:51.290526 (+0200) -0.833668 +/- 0.015501 141.144.241.16 s2= no-leap $ ntpdate -q 141.144.241.16 2026-04-06 13:08:56.136567 (+0200) -0.832294 +/- 0.014493 141.144.241.16 s2= no-leap $ ntpdate -q 141.144.241.16 2026-04-06 17:21:41.017554 (+0200) -1.044511 +/- 0.021817 141.144.241.16 s2= no-leap So, domU's clock definitely drifts. --=20 Best Regards, Marek Marczykowski-G=C3=B3recki Invisible Things Lab --F629bKJhvAiDwbl3 Content-Type: application/pgp-signature; name=signature.asc -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhrpukzGPukRmQqkK24/THMrX1ywFAmnT0XYACgkQ24/THMrX 1yynEwf/eRO74GKeVMvcaA9wOJKDjsLG/ZweEvDhjBWJRfwMXyWfOFb/CbUfBWDc CBcOa5DtGph5YQnU9ckWdyN16HlW0GiDSuY/X99KfcUpCFXaJLdxSLlJdRBXFHvh vinuBwUty868tWz8wED0OvRlmZOK6X8SwAi26ea6ur4FJ5JRC2Gjjv8efqY2HLjM kEqg5jxUCMSGivAl/HVrlYSIGiZZhQ6f0/647JlFMzww6zNS0Xvew+80egOQniqy rrOLtyrIWSnmHJj/dqAKfTmj2WwwWmgBJNpuU/LS93C16lgLqnUMHdxbCK2jfYu6 xJkXeln+ATuroCLIbyouNn+N59LlTw== =tz0q -----END PGP SIGNATURE----- --F629bKJhvAiDwbl3--