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stream: bitfield #29127
stream: bitfield #29127
Conversation
I need a little help/guidance on how to do or create relevant benchmarks. |
Haven't quite sorted out |
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If this is accepted we should probably do the same for |
Results don't look so good:
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Ah! I think I can run those. I’ll try manually inlining . |
@mscdex: After inlining, the worst case actually becomes an improvement: full benchmarks take way to long to run... streams/creation.js kind='duplex' n=1000000 ** 7.02 % ±4.09% ±5.46% ±7.13%
streams/creation.js kind='readable' n=1000000 *** 12.69 % ±3.33% ±4.44% ±5.81%
streams/creation.js kind='transform' n=1000000 ** 4.58 % ±3.21% ±4.28% ±5.57%
streams/readable-bigread.js n=1000 0.26 % ±1.52% ±2.03% ±2.64%
streams/readable-bigunevenread.js n=1000 *** 13.10 % ±6.64% ±8.83% ±11.49% I'm a little worried whether the cognitive overhead is worth the improved performance. Should I continue work on this? I think there is more I can get out of this in terms of pref & mem. |
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In the best case scenario this brings down the memory overhead: from 23 (184 bytes?):
to 5 (40 bytes? fits in cacheline):
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@Trott: WIP tag please :) |
I like the perf benefit, however I'm not really liking the added cognitive overhead of a bitfield. Can you try the http and fs benchmarks as well? |
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hah, that had quite a bit of variance |
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I don't think people would want the debug statements removed. |
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I thought it was the slow accessors that was the limiting factor. Re-added debug without slow accessors. Difference is small again: streams/readable-bigunevenread.js n=1000 ** 13.63 % ±8.98% ±11.95% ±15.55% I don't think I can get much more out of this... Although a fun exercise I'm not sure about the value of this... feel free to close |
Closing, but feel free to re-open if you change your mind! |
Tries to significantly reduce readable state size for lower memory overhead and possibly better performance.
I'm making the assumption here that V8 is able to inline getters and setters.
TODO:
- [ ] use localbitfield
instance to avoid property access throughstate
.Refs: #29126
Checklist
make -j4 test
(UNIX), orvcbuild test
(Windows) passes