c04e989484
When a grant entry is still in use by the remote domain, Linux must put it on a deferred list. Normally, this list is very short, because the PV network and block protocols expect the backend to unmap the grant first. However, Qubes OS's GUI protocol is subject to the constraints of the X Window System, and as such winds up with the frontend unmapping the window first. As a result, the list can grow very large, resulting in a massive memory leak and eventual VM freeze. To partially solve this problem, make the number of entries that the VM will attempt to free at each iteration tunable. The default is still 10, but it can be overridden via a module parameter. This is Cc: stable because (when combined with appropriate userspace changes) it fixes a severe performance and stability problem for Qubes OS users. Cc: stable@vger.kernel.org Signed-off-by: Demi Marie Obenour <demi@invisiblethingslab.com> Reviewed-by: Juergen Gross <jgross@suse.com> Link: https://lore.kernel.org/r/20230726165354.1252-1-demi@invisiblethingslab.com Signed-off-by: Juergen Gross <jgross@suse.com>
2.4 KiB
What: /sys/module/pch_phub/drivers/.../pch_mac Date: August 2010 KernelVersion: 2.6.35 Contact: masa-korg@dsn.okisemi.com Description: Write/read GbE MAC address.
What: /sys/module/pch_phub/drivers/.../pch_firmware Date: August 2010 KernelVersion: 2.6.35 Contact: masa-korg@dsn.okisemi.com Description: Write/read Option ROM data.
What: /sys/module/ehci_hcd/drivers/.../uframe_periodic_max Date: July 2011 KernelVersion: 3.1 Contact: Kirill Smelkov kirr@mns.spb.ru Description: Maximum time allowed for periodic transfers per microframe (μs)
Note:
USB 2.0 sets maximum allowed time for periodic transfers per
microframe to be 80%, that is 100 microseconds out of 125
microseconds (full microframe).
However there are cases, when 80% max isochronous bandwidth is
too limiting. For example two video streams could require 110
microseconds of isochronous bandwidth per microframe to work
together.
Through this setting it is possible to raise the limit so that
the host controller would allow allocating more than 100
microseconds of periodic bandwidth per microframe.
Beware, non-standard modes are usually not thoroughly tested by
hardware designers, and the hardware can malfunction when this
setting differ from default 100.
What: /sys/module/*/{coresize,initsize} Date: Jan 2012 KernelVersion: 3.3 Contact: Kay Sievers kay.sievers@vrfy.org Description: Module size in bytes.
What: /sys/module/*/initstate Date: Nov 2006 KernelVersion: 2.6.19 Contact: Kay Sievers kay.sievers@vrfy.org Description: Show the initialization state(live, coming, going) of the module.
What: /sys/module/*/taint Date: Jan 2012 KernelVersion: 3.3 Contact: Kay Sievers kay.sievers@vrfy.org Description: Module taint flags: == ===================== P proprietary module O out-of-tree module F force-loaded module C staging driver module E unsigned module == =====================
What: /sys/module/grant_table/parameters/free_per_iteration Date: July 2023 KernelVersion: 6.5 but backported to all supported stable branches Contact: Xen developer discussion xen-devel@lists.xenproject.org Description: Read and write number of grant entries to attempt to free per iteration.
Note: Future versions of Xen and Linux may provide a better
interface for controlling the rate of deferred grant reclaim
or may not need it at all.
Users: Qubes OS (https://www.qubes-os.org)