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Rapid window updates result in incorrect frame order in nested Sway sessions #3020
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Just to understand the bug better, does this wlroots patch help? https://l.sr.ht/qsvv.txt |
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Nope, the issue persists. |
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Okay, new attempt: https://l.sr.ht/BSq5.txt If this doesn't work, can you try |
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This patch fixes |
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Thanks for confirming this isn't a damage tracking issue. Here's yet another attempt: https://l.sr.ht/xcCP.txt. Can you try it? (Sorry, I'm having trouble reproducing reliably.) |
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This patch does fix the issue. |
emersion
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Right now we rely entirely on implicit sync for synchronizing access to GPU buffers. Implicit sync works by setting synchronization points on the buffer in writers, and letting readers wait on these sync points before accessing the buffer. With OpenGL, sync points are created using functions such as eglSwapBuffers or glFlush. If none of these special functions are called, no sync point will be created and readers will potentially access a buffer that hasn't finished rendering yet. In the context of wlroots, OpenGL is the writer and the backend (KMS or parent Wayland/X11 session) is the reader. After we're done rendering a frame, and before passing that frame to the backend, we need to call glFlush. glFlush is called when the buffer is detached from the renderer. This is a task done by output_clear_back_buffer. So let's call this function before invoking the impl->commit hook, instead of calling it after. All of this is maybe a little tricky to get right with the current renderer_bind_buffer API. The new wlr_renderer_begin_with_buffer API is much better, because glFlush is called on wlr_renderer_end, so it's more intuitive. Closes: swaywm#3020
emersion
added a commit
to emersion/wlroots
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this issue
Jul 7, 2021
Right now we rely entirely on implicit sync for synchronizing access to GPU buffers. Implicit sync works by setting synchronization points on the buffer in writers, and letting readers wait on these sync points before accessing the buffer. With OpenGL, sync points are created using functions such as eglSwapBuffers or glFlush. If none of these special functions are called, no sync point will be created and readers will potentially access a buffer that hasn't finished rendering yet. In the context of wlroots, OpenGL is the writer and the backend (KMS or parent Wayland/X11 session) is the reader. After we're done rendering a frame, and before passing that frame to the backend, we need to call glFlush. glFlush is called when the buffer is detached from the renderer. This is a task done by output_clear_back_buffer. So let's call this function before invoking the impl->commit hook, instead of calling it after. All of this is maybe a little tricky to get right with the current renderer_bind_buffer API. The new wlr_renderer_begin_with_buffer API is much better, because glFlush is called on wlr_renderer_end, so it's more intuitive. Closes: swaywm#3020
bl4ckb0ne
pushed a commit
that referenced
this issue
Jul 7, 2021
Right now we rely entirely on implicit sync for synchronizing access to GPU buffers. Implicit sync works by setting synchronization points on the buffer in writers, and letting readers wait on these sync points before accessing the buffer. With OpenGL, sync points are created using functions such as eglSwapBuffers or glFlush. If none of these special functions are called, no sync point will be created and readers will potentially access a buffer that hasn't finished rendering yet. In the context of wlroots, OpenGL is the writer and the backend (KMS or parent Wayland/X11 session) is the reader. After we're done rendering a frame, and before passing that frame to the backend, we need to call glFlush. glFlush is called when the buffer is detached from the renderer. This is a task done by output_clear_back_buffer. So let's call this function before invoking the impl->commit hook, instead of calling it after. All of this is maybe a little tricky to get right with the current renderer_bind_buffer API. The new wlr_renderer_begin_with_buffer API is much better, because glFlush is called on wlr_renderer_end, so it's more intuitive. Closes: #3020
emersion
added a commit
to emersion/wlroots
that referenced
this issue
Jul 7, 2021
Right now we rely entirely on implicit sync for synchronizing access to GPU buffers. Implicit sync works by setting synchronization points on the buffer in writers, and letting readers wait on these sync points before accessing the buffer. With OpenGL, sync points are created using functions such as eglSwapBuffers or glFlush. If none of these special functions are called, no sync point will be created and readers will potentially access a buffer that hasn't finished rendering yet. In the context of wlroots, OpenGL is the writer and the backend (KMS or parent Wayland/X11 session) is the reader. After we're done rendering a frame, and before passing that frame to the backend, we need to call glFlush. glFlush is called when the buffer is detached from the renderer. This is a task done by output_clear_back_buffer. So let's call this function before invoking the impl->commit hook, instead of calling it after. All of this is maybe a little tricky to get right with the current renderer_bind_buffer API. The new wlr_renderer_begin_with_buffer API is much better, because glFlush is called on wlr_renderer_end, so it's more intuitive. Closes: swaywm#3020 (cherry picked from commit c2bd63c)
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sway -c /dev/null)Description
Sometimes Sway renders frames out of order when run with a Wayland/X11 backend, resulting in older frames being seen after newer ones. At least, that's what it looks like.
Reproduction
weston-terminal(or any other program capable of updating its window contents rapidly)Frame 1:
$ aaaaaaaaaaFrame 2:
$ aaaaaaFrame 3:
$ aaaaaaaaaaaaaaaaThis isn't reproducible with Sway 1.6 or when the DRM backend is used.
Notes
-D damage=highlighthas no effect for nested Sway sessions, which may or may not be related to this. Also introduced with the wlroots commit mentioned above.cpulimit -l 1 sway -c /dev/null).The text was updated successfully, but these errors were encountered: