[Bug 60522] New: winebus.sys: input report queue never drops old reports, causing growing controller lag

[WineHQ Bugzilla]

http://bugs.winehq.org/show_bug.cgi?id=60522

            Bug ID: 60522
           Summary: winebus.sys: input report queue never drops old
                    reports, causing growing controller lag
           Product: Wine
           Version: 11.20
          Hardware: x86-64
                OS: MacOS
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: hid
          Assignee: [e-mail]
          Reporter: [e-mail]
  Target Milestone: ---

winebus queues every input report in ext->reports (process_hid_report in
dlls/winebus.sys/main.c) and never drops any. If a device sends reports faster
than they get read, the queue just keeps growing and the game sees older and
older input.

How I hit it: Steam Controller through Steam Input on macOS. Steam's virtual
Xbox pad (045E/028E, picked up by the IOHID backend) sends a report for every
little stick jitter, around 830/s even when you're barely moving. Under load,
delivery to hidclass drops to roughly 520-700/s and the backlog never recovers.

From a +hid trace of a Diablo IV session:
- the queue peaked at ~14,700 reports, about 17 s of input lag
- it only clears when Steam stops sending (alt-tab, quit), and then it drains
  at ~4,000 reports/s

Native's HID class keeps input reports in a ring buffer (32 reports by default,
see IOCTL_SET_NUM_DEVICE_INPUT_BUFFERS), so stale input can't pile up like
this.
Wine's own hidclass already does the same per handle.

Seen on CrossOver 27 builds (Wine 11.15 and 11.17 based); process_hid_report is
the same on current master. MR to follow.

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[Bug 60522] winebus.sys: input report queue never drops old reports, causing growing controller lag

[WineHQ Bugzilla]

http://bugs.winehq.org/show_bug.cgi?id=60522

Thomas Cool <[e-mail]> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Hardware|x86-64                      |arm

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