289147 2025-03-04 22:54:51 -0800 [WebGPU] Memory barriers in vertex shader validation routines are problematic on M1 2025-03-10 08:27:53 -0700 1 1 1 Unclassified WebKit WebGPU WebKit Nightly Build Unspecified Unspecified RESOLVED FIXED InRadar P2 Normal --- 1 mwyrzykowski mwyrzykowski mwyrzykowski tzagallo webkit-bug-importer oldest_to_newest 2100530 0 mwyrzykowski 2025-03-04 22:54:51 -0800 [WebGPU] Visual difference on some sites between M1 and M2 Macs 2100531 1 webkit-bug-importer 2025-03-04 22:55:07 -0800 <rdar://problem/146219177> 2100533 2 mwyrzykowski 2025-03-04 23:01:42 -0800 M1s are triggering a context lost due to MTLCommandBuffer failure: error 23:00:40.699875-0800 com.apple.WebKit.GPU -[_MTLCommandBuffer didScheduleWithStartTime:endTime:error:], line 1020: error 'Execution of the command buffer was aborted due to an error during execution. Internal Error (00000100:Internal Error)' error 23:00:40.699908-0800 com.apple.WebKit.GPU Execution of the command buffer was aborted due to an error during execution. Internal Error (00000100:Internal Error) default 23:00:40.719243-0800 com.apple.WebKit.GPU Encountered fatal command buffer error Error Domain=MTLCommandBufferErrorDomain Code=1 "Internal Error (00000100:Internal Error)" UserInfo={NSLocalizedDescription=Internal Error (00000100:Internal Error), NSUnderlyingError=0x7067adcb0 {Error Domain=IOGPUCommandQueueErrorDomain Code=256 "(null)"}}, underlying error Error Domain=IOGPUCommandQueueErrorDomain Code=256 "(null)" 2100757 3 mwyrzykowski 2025-03-05 14:58:57 -0800 If we ignore this error on M1s the page works as expected, need to figure out what error code 256 is ``` Encountered non-fatal command buffer error Error Domain=MTLCommandBufferErrorDomain Code=1 "Internal Error (00000100:Internal Error)" UserInfo={NSLocalizedDescription=Internal Error (00000100:Internal Error), NSUnderlyingError=0x42dd31fb0 {Error Domain=IOGPUCommandQueueErrorDomain Code=256 "(null)"}}, underlying error Error Domain=IOGPUCommandQueueErrorDomain Code=256 "(null)" Encountered non-fatal command buffer error Error Domain=MTLCommandBufferErrorDomain Code=1 "Internal Error (00000100:Internal Error)" UserInfo={NSLocalizedDescription=Internal Error (00000100:Internal Error), NSUnderlyingError=0x43510cb00 {Error Domain=IOGPUCommandQueueErrorDomain Code=256 "(null)"}}, underlying error Error Domain=IOGPUCommandQueueErrorDomain Code=256 "(null)" Encountered non-fatal command buffer error Error Domain=MTLCommandBufferErrorDomain Code=1 "Internal Error (00000100:Internal Error)" UserInfo={NSLocalizedDescription=Internal Error (00000100:Internal Error), NSUnderlyingError=0x42ddf50e0 {Error Domain=IOGPUCommandQueueErrorDomain Code=256 "(null)"}}, underlying error Error Domain=IOGPUCommandQueueErrorDomain Code=256 "(null)" Encountered non-fatal command buffer error Error Domain=MTLCommandBufferErrorDomain Code=1 "Internal Error (00000100:Internal Error)" UserInfo={NSLocalizedDescription=Internal Error (00000100:Internal Error), NSUnderlyingError=0x142c9c810 {Error Domain=IOGPUCommandQueueErrorDomain Code=256 "(null)"}}, underlying error Error Domain=IOGPUCommandQueueErrorDomain Code=256 "(null)" Encountered non-fatal command buffer error Error Domain=MTLCommandBufferErrorDomain Code=1 "Internal Error (00000100:Internal Error)" UserInfo={NSLocalizedDescription=Internal Error (00000100:Internal Error), NSUnderlyingError=0x436b94e40 {Error Domain=IOGPUCommandQueueErrorDomain Code=256 "(null)"}}, underlying error Error Domain=IOGPUCommandQueueErrorDomain Code=256 "(null)" Encountered non-fatal command buffer error Error Domain=MTLCommandBufferErrorDomain Code=1 "Internal Error (00000100:Internal Error)" UserInfo={NSLocalizedDescription=Internal Error (00000100:Internal Error), NSUnderlyingError=0x142ca24f0 {Error Domain=IOGPUCommandQueueErrorDomain Code=256 "(null)"}}, underlying error Error Domain=IOGPUCommandQueueErrorDomain Code=256 "(null)" com.apple.WebKit.GPU.Development(40094) MallocStackLogging: msl_handle_memory_pressure_event: approaching memory limit. Starting stack-logging. ``` 2101056 4 mwyrzykowski 2025-03-06 10:57:07 -0800 Ok great I root caused it. Too many completion handlers are being added to the MTLCommandBuffer, which appears to be exhausting some driver / kernel resource. WebKit can manage this ourselves quite easily, I will change that 2101204 5 mwyrzykowski 2025-03-06 16:29:18 -0800 Further analysis indicates this is not due to the total number of completion handlers, but rather the way we are using memory barriers does not seem to work on M1 Macs. We could split passes on M1s as this is not a codepath which should not be regularly triggered 2101209 6 mwyrzykowski 2025-03-06 16:45:29 -0800 Splitting render passes to validate like we do for Intel appears to resolve the issue. 2101276 7 mwyrzykowski 2025-03-06 21:30:04 -0800 Splitting the render passes is not needed, there is a simpler solution, I will implement that instead 2101281 8 mwyrzykowski 2025-03-06 21:48:03 -0800 Pull request: https://github.com/WebKit/WebKit/pull/42069 2101927 9 ews-feeder 2025-03-10 08:27:50 -0700 Committed 291897@main (8f1919db1fce): <https://commits.webkit.org/291897@main> Reviewed commits have been landed. Closing PR #42069 and removing active labels.