paging: make ALL levels writable, not just P4#2214
paging: make ALL levels writable, not just P4#2214zyuiop wants to merge 1 commit intohermit-os:mainfrom
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Does this work correctly in the presence of reserved (by boot-loader) read-only memory? |
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Benchmark Results
Details
| Benchmark | Current: b46fc5d | Previous: f017c04 | Performance Ratio |
|---|---|---|---|
| startup_benchmark Build Time | 98.91 s |
100.00 s |
0.99 ❗ |
| startup_benchmark File Size | 0.86 MB |
0.86 MB |
1.00 ❗ |
| Startup Time - 1 core | 0.93 s (±0.03 s) |
0.96 s (±0.03 s) |
0.97 |
| Startup Time - 2 cores | 0.95 s (±0.03 s) |
0.96 s (±0.03 s) |
0.99 |
| Startup Time - 4 cores | 0.94 s (±0.03 s) |
0.96 s (±0.03 s) |
0.98 |
| multithreaded_benchmark Build Time | 100.47 s |
101.55 s |
0.99 ❗ |
| multithreaded_benchmark File Size | 0.96 MB |
0.96 MB |
1.00 ❗ |
| Multithreaded Pi Efficiency - 2 Threads | 91.19 % (±8.48 %) |
88.90 % (±8.32 %) |
1.03 |
| Multithreaded Pi Efficiency - 4 Threads | 43.95 % (±3.61 %) |
43.88 % (±2.75 %) |
1.00 |
| Multithreaded Pi Efficiency - 8 Threads | 25.75 % (±1.89 %) |
25.66 % (±1.89 %) |
1.00 |
| micro_benchmarks Build Time | 95.09 s |
100.99 s |
0.94 ❗ |
| micro_benchmarks File Size | 0.97 MB |
0.97 MB |
1.00 ❗ |
| Scheduling time - 1 thread | 67.01 ticks (±3.71 ticks) |
69.86 ticks (±3.37 ticks) |
0.96 |
| Scheduling time - 2 threads | 38.86 ticks (±5.68 ticks) |
40.31 ticks (±6.77 ticks) |
0.96 |
| Micro - Time for syscall (getpid) | 3.92 ticks (±0.41 ticks) |
3.96 ticks (±0.50 ticks) |
0.99 |
| Memcpy speed - (built_in) block size 4096 | 67239.64 MByte/s (±47785.51 MByte/s) |
65275.34 MByte/s (±46520.56 MByte/s) |
1.03 |
| Memcpy speed - (built_in) block size 1048576 | 29668.49 MByte/s (±24208.03 MByte/s) |
29541.10 MByte/s (±24264.88 MByte/s) |
1.00 |
| Memcpy speed - (built_in) block size 16777216 | 28524.40 MByte/s (±23715.64 MByte/s) |
24775.73 MByte/s (±20842.74 MByte/s) |
1.15 |
| Memset speed - (built_in) block size 4096 | 68250.71 MByte/s (±48513.16 MByte/s) |
66091.92 MByte/s (±47089.66 MByte/s) |
1.03 |
| Memset speed - (built_in) block size 1048576 | 30423.69 MByte/s (±24628.09 MByte/s) |
30293.21 MByte/s (±24687.70 MByte/s) |
1.00 |
| Memset speed - (built_in) block size 16777216 | 29290.73 MByte/s (±24148.29 MByte/s) |
25550.97 MByte/s (±21347.58 MByte/s) |
1.15 |
| Memcpy speed - (rust) block size 4096 | 60931.32 MByte/s (±44862.89 MByte/s) |
58754.84 MByte/s (±43359.45 MByte/s) |
1.04 |
| Memcpy speed - (rust) block size 1048576 | 29394.50 MByte/s (±24111.70 MByte/s) |
29244.90 MByte/s (±24125.53 MByte/s) |
1.01 |
| Memcpy speed - (rust) block size 16777216 | 28529.04 MByte/s (±23725.01 MByte/s) |
25398.03 MByte/s (±21360.45 MByte/s) |
1.12 |
| Memset speed - (rust) block size 4096 | 61741.04 MByte/s (±45345.78 MByte/s) |
59191.17 MByte/s (±43611.85 MByte/s) |
1.04 |
| Memset speed - (rust) block size 1048576 | 30147.72 MByte/s (±24536.09 MByte/s) |
29995.68 MByte/s (±24557.30 MByte/s) |
1.01 |
| Memset speed - (rust) block size 16777216 | 29284.98 MByte/s (±24148.89 MByte/s) |
26167.61 MByte/s (±21843.64 MByte/s) |
1.12 |
| alloc_benchmarks Build Time | 92.89 s |
99.83 s |
0.93 ❗ |
| alloc_benchmarks File Size | 0.94 MB |
0.93 MB |
1.00 ❗ |
| Allocations - Allocation success | 100.00 % |
100.00 % |
1 |
| Allocations - Deallocation success | 100.00 % |
100.00 % |
1 |
| Allocations - Pre-fail Allocations | 100.00 % |
100.00 % |
1 |
| Allocations - Average Allocation time | 9455.00 Ticks (±161.71 Ticks) |
9424.02 Ticks (±112.49 Ticks) |
1.00 |
| Allocations - Average Allocation time (no fail) | 9455.00 Ticks (±161.71 Ticks) |
9424.02 Ticks (±112.49 Ticks) |
1.00 |
| Allocations - Average Deallocation time | 1848.79 Ticks (±500.69 Ticks) |
1052.94 Ticks (±452.14 Ticks) |
1.76 ❗ |
| mutex_benchmark Build Time | 96.90 s |
99.82 s |
0.97 ❗ |
| mutex_benchmark File Size | 0.97 MB |
0.97 MB |
1.00 ❗ |
| Mutex Stress Test Average Time per Iteration - 1 Threads | 13.22 ns (±0.64 ns) |
13.02 ns (±0.55 ns) |
1.02 |
| Mutex Stress Test Average Time per Iteration - 2 Threads | 13.80 ns (±0.80 ns) |
13.62 ns (±0.77 ns) |
1.01 |
This comment was automatically generated by workflow using github-action-benchmark.
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Wait, is the title of this PR misleading and this does make all levels including-and-below P4 writable, but doesn't touch anything else? |
Not sure. I think the best fix would be to remap memory and not reuse the boot-loader mapping, or at least use an offset map for accessing page tables, as currently it is a bit weird. |
I agree. I was planning to do this anyway with the next loader release. This PR is still useful for you in the meantime, right? |
How is the title misleading? |
I have it in my fork as well, so it's okay! |
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I did say what I find misleading in the rest of the sentence, what information is still missing? |
This PR is about making more of the page table writable. This is not about actually writing to any reserved memory or marking the memory as available in our physical memory management structures. Is it clearer now? "This does make all levels including-and-below P4 writable, but doesn't touch anything else" sounds the same as the title to me, so I am confused about what you mean. In any case, let's see how quickly the loader is progressing. We can keep the PR open until it is resolved. In case we find any issues with the plan, we can merge it. |
After investigating PF exceptions, I traced them back to a
pt.set_unused()call, which failed because the page table was not entirely writable.