lseek: Fixed incorrect lseek behaviour with whence Set or Cur #1934
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Benchmark Results
| Benchmark | Current: c441518 | Previous: 250f22e | Performance Ratio |
|---|---|---|---|
| startup_benchmark Build Time | 137.67 s |
124.48 s |
1.11 |
| startup_benchmark File Size | 0.91 MB |
0.91 MB |
1.00 |
| Startup Time - 1 core | 0.94 s (±0.01 s) |
0.93 s (±0.02 s) |
1.01 |
| Startup Time - 2 cores | 0.95 s (±0.02 s) |
0.93 s (±0.03 s) |
1.02 |
| Startup Time - 4 cores | 0.96 s (±0.02 s) |
0.95 s (±0.02 s) |
1.01 |
| multithreaded_benchmark Build Time | 139.44 s |
122.65 s |
1.14 |
| multithreaded_benchmark File Size | 1.02 MB |
1.02 MB |
1.00 |
| Multithreaded Pi Efficiency - 2 Threads | 3.22 % (±15.47 %) |
2.79 % (±13.37 %) |
1.16 |
| Multithreaded Pi Efficiency - 4 Threads | 1.76 % (±8.46 %) |
1.58 % (±7.57 %) |
1.12 |
| Multithreaded Pi Efficiency - 8 Threads | 0.85 % (±4.10 %) |
0.82 % (±3.93 %) |
1.04 |
| micro_benchmarks Build Time | 171.86 s |
145.61 s |
1.18 |
| micro_benchmarks File Size | 1.02 MB |
1.03 MB |
1.00 |
| Scheduling time - 1 thread | 3.78 ticks (±18.15 ticks) |
3.05 ticks (±14.65 ticks) |
1.24 |
| Scheduling time - 2 threads | 1.57 ticks (±7.53 ticks) |
1.56 ticks (±7.50 ticks) |
1.00 |
| Micro - Time for syscall (getpid) | 0.20 ticks (±0.94 ticks) |
0.18 ticks (±0.86 ticks) |
1.09 |
| Memcpy speed - (built_in) block size 4096 | 1250.00 MByte/s (±6000.00 MByte/s) |
1313.03 MByte/s (±6302.52 MByte/s) |
0.95 |
| Memcpy speed - (built_in) block size 1048576 | 554.00 MByte/s (±2659.21 MByte/s) |
692.52 MByte/s (±3324.10 MByte/s) |
0.80 |
| Memcpy speed - (built_in) block size 16777216 | 205.21 MByte/s (±984.99 MByte/s) |
211.07 MByte/s (±1013.12 MByte/s) |
0.97 |
| Memset speed - (built_in) block size 4096 | 1290.32 MByte/s (±6193.55 MByte/s) |
1290.32 MByte/s (±6193.55 MByte/s) |
1 |
| Memset speed - (built_in) block size 1048576 | 1339.18 MByte/s (±6428.07 MByte/s) |
1331.78 MByte/s (±6392.54 MByte/s) |
1.01 |
| Memset speed - (built_in) block size 16777216 | 873.30 MByte/s (±4191.82 MByte/s) |
866.63 MByte/s (±4159.85 MByte/s) |
1.01 |
| Memcpy speed - (rust) block size 4096 | 1304.35 MByte/s (±6260.87 MByte/s) |
960.00 MByte/s (±4608.00 MByte/s) |
1.36 |
| Memcpy speed - (rust) block size 1048576 | 501.56 MByte/s (±2407.49 MByte/s) |
562.78 MByte/s (±2701.33 MByte/s) |
0.89 |
| Memcpy speed - (rust) block size 16777216 | 206.11 MByte/s (±989.32 MByte/s) |
203.06 MByte/s (±974.70 MByte/s) |
1.01 |
| Memset speed - (rust) block size 4096 | 1578.95 MByte/s (±7578.95 MByte/s) |
1500.00 MByte/s (±7200.00 MByte/s) |
1.05 |
| Memset speed - (rust) block size 1048576 | 979.55 MByte/s (±4701.85 MByte/s) |
1289.16 MByte/s (±6187.96 MByte/s) |
0.76 |
| Memset speed - (rust) block size 16777216 | 880.28 MByte/s (±4225.35 MByte/s) |
882.37 MByte/s (±4235.38 MByte/s) |
1.00 |
| alloc_benchmarks Build Time | 159.83 s |
141.09 s |
1.13 |
| alloc_benchmarks File Size | 0.98 MB |
0.98 MB |
1.00 |
| Allocations - Allocation success | 2.00 % (±13.86 %) |
2.00 % (±13.86 %) |
1 |
| Allocations - Deallocation success | 1.40 % (±9.69 %) |
1.40 % (±9.74 %) |
1.00 |
| Allocations - Pre-fail Allocations | 2.00 % (±13.86 %) |
2.00 % (±13.86 %) |
1 |
| Allocations - Average Allocation time | 261.32 Ticks (±1810.83 Ticks) |
245.11 Ticks (±1698.52 Ticks) |
1.07 |
| Allocations - Average Allocation time (no fail) | 261.32 Ticks (±1810.83 Ticks) |
245.11 Ticks (±1698.52 Ticks) |
1.07 |
| Allocations - Average Deallocation time | 17.32 Ticks (±119.99 Ticks) |
17.05 Ticks (±118.16 Ticks) |
1.02 |
| mutex_benchmark Build Time | 156.02 s |
142.06 s |
1.10 |
| mutex_benchmark File Size | 1.03 MB |
1.03 MB |
1.00 |
| Mutex Stress Test Average Time per Iteration - 1 Threads | 0.30 ns (±2.08 ns) |
0.34 ns (±2.36 ns) |
0.88 |
| Mutex Stress Test Average Time per Iteration - 2 Threads | 0.38 ns (±2.63 ns) |
0.36 ns (±2.49 ns) |
1.06 |
This comment was automatically generated by workflow using github-action-benchmark.
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I had buggy code that was using lseek.
Turns out, FUSE is a little odd in that regard (I might be wrong, but this is how it looks to me):
preadv64internally)Lseekdoes exist in FUSE and in virtiofsd it maps to the host'slseek. It also returns the host'slseekreturn value.lseekwith aCurwhence doesn't return a meaningful value.lseekto the deamon is not sufficient for seeking through a file (we already use an internal offset correctly in these cases).This PR fixes the incorrect behaviour in lseek by:
SetandCur.This should have a slightly positive effect on the performance, since it reduces virtio transactions.
Note that this is not tested for
DataandHole, so these might still be buggy.