1604260386659880961

2026-08-26 10:56:05 -04:00
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+---
+title: "@NOTimothyLottes cool!"
+type: archive
+source: twitter
+source_url: "https://x.com/abductee_org/status/1604899144786620416"
+author: "Michael Sänger (💉 3/2)"
+handle: abductee_org
+post_id: "1604899144786620416"
+date: 2022-12-19
+archived: 2026-08-26
+draft: false
+tags:
+  - archive
+  - twitter
+  - NOTimothyLottes
+description: "@NOTimothyLottes cool!"
+in_reply_to: ""
+parent_post_id: "1604260386659880961"
+---
+
+## Source
+
+- URL: https://x.com/abductee_org/status/1604899144786620416
+- Author: Michael Sänger (💉 3/2) (@abductee_org)
+- Posted: 2022-12-19 17:59:08
+
+## Branch
+
+**1/** **@abductee_org** ^1604899144786620416
+
+**@NOTimothyLottes**
+
+cool!
+any similar comments on cuda12/ptx/sass? ;)
+
+**2/** **@NOTimothyLottes** ^1605588165384814592
+
+**@abductee_org**
+
+https://x.com/NOTimothyLottes/status/1596096198758244352 and https://x.com/NOTimothyLottes/status/1596094389641965570
+
+## Related
+
+- Spine: [[archive/threads/NOTimothyLottes/2022-12-17-rdna3-isa-guide-comments]]
@@ -0,0 +1,53 @@
+---
+title: "RDNA3 ISA Guide Comments"
+type: archive
+source: twitter
+source_url: "https://x.com/NOTimothyLottes/status/1604260386659880961"
+author: "NOTimothyLottes"
+handle: NOTimothyLottes
+post_id: "1604260386659880961"
+date: 2022-12-17
+archived: 2026-08-26
+draft: false
+tags:
+  - archive
+  - twitter
+  - NOTimothyLottes
+description: "RDNA3 ISA Guide Comments"
+in_reply_to: ""
+---
+
+## Source
+
+- URL: https://x.com/NOTimothyLottes/status/1604260386659880961
+- Author: NOTimothyLottes (@NOTimothyLottes)
+- Posted: 2022-12-17 23:40:56
+
+## Thread
+
+**1/** **@NOTimothyLottes** ^1604260386659880961
+
+RDNA3 ISA Guide Comments
+(1.) Driver: Instead of padding 256 bytes with S_CODE_END, how about putting the next shader in there (looking at you post process passes, with consistent temporal ordering).
+
+Branches: [[archive/threads/NOTimothyLottes/2022-12-17-rdna3-isa-guide-comments/2022-12-19-abductee_org-cool-any-similar-comments-on-cuda12-ptx-sass]]
+
+**2/** **@NOTimothyLottes** ^1604263778106892292
+
+(2.) VGPR increase: Traditionally with 8 VGPR allocation granularity the target would be 64 VGPRs/wave or under. Now with 12 granularity a compiler can likely miss the 64 VGPR target and get to 96 without seeing a problem in those cases.
+
+**3/** **@NOTimothyLottes** ^1604265437281271809
+
+(3.) S_MEMREALTIME went to S_SENDMSG_RTN+S_WAITCNT (side effect, more opcode space), these would include a code motion barrier anyway. Would like a VK extension to query the "typically 100 MHz" fixed frequency amount: lots of nice things you can do with a real shader wallclock!
+
+**4/** **@NOTimothyLottes** ^1604267130299596803
+
+(4.) Really nice cache control via {SRD llc_noalloc, opcode DLC/SLC/GLC}. Wish there was a way to access using layout qualifier aliasing in VK. Esp 'STREAM' on loads, to avoid cache pollution when no reuse is known by the developer.
+
+**5/** **@NOTimothyLottes** ^1604268044464930817
+
+(5.) "Dealloc VGPRs" - CS waves need to wait until all pending stores return "finished" before the wave exits. But now the VGPRs can be returned before waiting (to be used by a new workgroup). However, persistent or semi-persistent waves is still the way to go IMO.
+
+**6/** **@NOTimothyLottes** ^1604485986234388481
+
+(6.) V_PERMLANE64 - Likely no more V_READLANE waterfall for dynamic index shuffle in Wave64 mode (don't have a RDNA3 to dump disassembly), but will LDS still be faster than the complex sequence of {PERMLANE16, PERMLANEX16, PERMLANE64} related logic?
@@ -14,6 +14,7 @@ tags:
 - [[archive/threads/NOTimothyLottes/2022-11-08-example-of-bind-everything-once-layout-aliasing]]
 - [[archive/threads/NOTimothyLottes/2022-11-09-if-only-pc-vendors-with-open-isas]]
 - [[archive/threads/NOTimothyLottes/2022-11-13-my-prefered-method-of-managing-application-data]]
+- [[archive/threads/NOTimothyLottes/2022-12-17-rdna3-isa-guide-comments]]
 - [[archive/threads/NOTimothyLottes/2023-04-28-https-gpuopen-com-learn-rgp-1-15-enhanced-isa]]
 - [[archive/threads/NOTimothyLottes/2023-05-03-found-some-of-my-old-blogs-thread-looking-back-an]]
 - [[archive/threads/NOTimothyLottes/2023-06-20-how-about-a-mega-thread-on-the-mechanics-of-cpu]]