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Wed, 29 Jul 2026 10:29:10 -0400 (EDT) Received: by fw12.qyliss.net (Postfix, from userid 1000) id 55851C4E715E; Wed, 29 Jul 2026 16:29:09 +0200 (CEST) From: Alyssa Ross To: Demi Marie Obenour Subject: Re: [PATCH v4 09/20] host/rootfs: Set up parent cgroup for all per-VM services In-Reply-To: References: <20260721-cgroups-v4-0-46b2e5fff7b6@gmail.com> <20260721-cgroups-v4-9-46b2e5fff7b6@gmail.com> <871pcoljat.fsf@alyssa.is> Date: Wed, 29 Jul 2026 16:29:07 +0200 Message-ID: <875x1x6f9o.fsf@alyssa.is> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha512; protocol="application/pgp-signature" Message-ID-Hash: LSZ7VEMKUBWF3GAUCY5XJ35DCVXLRBDO X-Message-ID-Hash: LSZ7VEMKUBWF3GAUCY5XJ35DCVXLRBDO X-MailFrom: hi@alyssa.is X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; loop; banned-address; header-match-devel.spectrum-os.org-0; header-match-devel.spectrum-os.org-1; header-match-devel.spectrum-os.org-2; header-match-devel.spectrum-os.org-3; header-match-devel.spectrum-os.org-4; emergency; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: Spectrum OS Development X-Mailman-Version: 3.3.10 Precedence: list List-Id: Patches and low-level development discussion Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable Demi Marie Obenour writes: > On 7/27/26 08:16, Alyssa Ross wrote: >> Demi Marie Obenour writes: >>=20 >>> Signed-off-by: Demi Marie Obenour >>> --- >>> host/rootfs/image/etc/s6-linux-init/run-image/service/vm-services/run = | 3 +++ >>> 1 file changed, 3 insertions(+) >>> >>> diff --git a/host/rootfs/image/etc/s6-linux-init/run-image/service/vm-s= ervices/run b/host/rootfs/image/etc/s6-linux-init/run-image/service/vm-serv= ices/run >>> index 78f794202bf174f3c036f3e20755ac087a988277..430065b1efae8ce1fe7c7a0= 7b67920daa88bf98c 100755 >>> --- a/host/rootfs/image/etc/s6-linux-init/run-image/service/vm-services= /run >>> +++ b/host/rootfs/image/etc/s6-linux-init/run-image/service/vm-services= /run >>> @@ -1,5 +1,8 @@ >>> #!/bin/execlineb -WP >>> # SPDX-License-Identifier: EUPL-1.2+ >>> # SPDX-FileCopyrightText: 2023 Alyssa Ross >>> +# SPDX-FileCopyrightText: 2026 Demi Marie Obenour >>>=20=20 >>> +# Set up the parent cgroup of all VMMs and VM services >>> +cgroup-setup --no-wait -- /vm-services.slice >>> s6-svscan -d3 instance >>=20 >> We wouldn't want to wait if vm-services was restarted? (I'm not sure >> either way, would just like to read the reasoning.) > > cgroup-setup waits for the cgroup *and all of its transitive child > cgroups* to become empty. Therefore, waiting would block until all > VMMs had exited and all of their services had stopped. > > Even if it only waited on /vm-service.slice/$inner.service to become > empty, it would still wait for all of the s6-supervise processes in > that cgroup to exit. That's unlikely to ever happen. > > Running more than one instance of s6-svscan (or s6-supervise) is > harmless: the program immediately exits with status 100. That will > cause it to be restarted indefinitely, consuming CPU. However, I > don't know a good alternative unless s6 gets support for bind-mounted > pidfds, allowing s6-svscan and s6-supervise to keep track of child > processes across restarts. Why is this different to the top-level vmm service? It also just runs s6-svscan, but it does not use --no-wait. --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEARYKAB0WIQQGoGac7QfI+H5ZtFCZddwkt31pFQUCamoOMwAKCRCZddwkt31p FQXDAP4/6YrHNfVOgM2ToVRaYJ6qSEAo7gbPH8cc+D/gNnFeygD7BWAoLi6Njl4Z /w4z/vRty0599YbZ33rnSj68vpF+aAs= =h77K -----END PGP SIGNATURE----- --=-=-=--