Re: [RESEND] [PATCH] readahead:add blk_run_backing_dev

Wu Fengguang
2009-06-29T15:01:53Z

On Mon, Jun 29, 2009 at 10:21:24PM +0800, Wu Fengguang wrote:
> On Mon, Jun 29, 2009 at 10:00:20PM +0800, Ronald Moesbergen wrote:
> > ... tests ...
> >
> > > We started with 2.6.29, so why not complete with it (to save additional
> > > Ronald's effort to move on 2.6.30)?
> > >
> > >>> 2. Default vanilla 2.6.29 kernel, 512 KB read-ahead, the rest is default
> > >>
> > >> How about 2MB RAID readahead size? That transforms into about 512KB
> > >> per-disk readahead size.
> > >
> > > OK. Ronald, can you 4 more test cases, please:
> > >
> > > 7. Default vanilla 2.6.29 kernel, 2MB read-ahead, the rest is default
> > >
> > > 8. Default vanilla 2.6.29 kernel, 2MB read-ahead, 64 KB
> > > max_sectors_kb, the rest is default
> > >
> > > 9. Patched by the Fengguang's patch vanilla 2.6.29 kernel, 2MB
> > > read-ahead, the rest is default
> > >
> > > 10. Patched by the Fengguang's patch vanilla 2.6.29 kernel, 2MB
> > > read-ahead, 64 KB max_sectors_kb, the rest is default
> >
> > The results:
>
> I made a blindless average:
>
> N MB/s IOPS case
>
> 0 114.859 984.148 Unpatched, 128KB readahead, 512 max_sectors_kb
> 1 122.960 981.213 Unpatched, 512KB readahead, 512 max_sectors_kb
> 2 120.709 985.111 Unpatched, 2MB readahead, 512 max_sectors_kb
> 3 158.732 1004.714 Unpatched, 512KB readahead, 64 max_sectors_kb
> 4 159.237 979.659 Unpatched, 2MB readahead, 64 max_sectors_kb
>
> 5 114.583 982.998 Patched, 128KB readahead, 512 max_sectors_kb
> 6 124.902 987.523 Patched, 512KB readahead, 512 max_sectors_kb
> 7 127.373 984.848 Patched, 2MB readahead, 512 max_sectors_kb
> 8 161.218 986.698 Patched, 512KB readahead, 64 max_sectors_kb
> 9 163.908 574.651 Patched, 2MB readahead, 64 max_sectors_kb
>
> So before/after patch:
>
> avg throughput 135.299 => 138.397 by +2.3%
> avg IOPS 986.969 => 903.344 by -8.5%
>
> The IOPS is a bit weird.
>
> Summaries:
> - this patch improves RAID throughput by +2.3% on average
> - after this patch, 2MB readahead performs slightly better
> (by 1-2%) than 512KB readahead

and the most important one:
- 64 max_sectors_kb performs much better than 256 max_sectors_kb, by ~30% !

Thanks,
Fengguang

> > Unpatched, 128KB readahead, 512 max_sectors_kb
> > blocksize R R R R(avg, R(std R
> > (bytes) (s) (s) (s) MB/s) ,MB/s) (IOPS)
> > 67108864 5.621 5.503 5.419 185.744 2.780 2.902
> > 33554432 6.628 5.897 6.242 164.068 7.827 5.127
> > 16777216 7.312 7.165 7.614 139.148 3.501 8.697
> > 8388608 8.719 8.408 8.694 119.003 1.973 14.875
> > 4194304 11.836 12.192 12.137 84.958 1.111 21.239
> > 2097152 13.452 13.992 14.035 74.090 1.442 37.045
> > 1048576 12.759 11.996 12.195 83.194 2.152 83.194
> > 524288 11.895 12.297 12.587 83.570 1.945 167.140
> > 262144 7.325 7.285 7.444 139.304 1.272 557.214
> > 131072 7.992 8.832 7.952 124.279 5.901 994.228
> > 65536 10.940 10.062 10.122 98.847 3.715 1581.545
> > 32768 9.973 10.012 9.945 102.640 0.281 3284.493
> > 16384 11.377 10.538 10.692 94.316 3.100 6036.222
> >
> > Unpatched, 512KB readahead, 512 max_sectors_kb
> > blocksize R R R R(avg, R(std R
> > (bytes) (s) (s) (s) MB/s) ,MB/s) (IOPS)
> > 67108864 5.032 4.770 5.265 204.228 8.271 3.191
> > 33554432 5.569 5.712 5.863 179.263 3.755 5.602
> > 16777216 6.661 6.857 6.550 153.132 2.888 9.571
> > 8388608 8.022 8.000 7.978 127.998 0.288 16.000
> > 4194304 10.959 11.579 12.208 88.586 3.902 22.146
> > 2097152 13.692 12.670 12.625 78.906 2.914 39.453
> > 1048576 11.120 11.144 10.878 92.703 1.018 92.703
> > 524288 11.234 10.915 11.374 91.667 1.587 183.334
> > 262144 6.848 6.678 6.795 151.191 1.594 604.763
> > 131072 7.393 7.367 7.337 139.025 0.428 1112.202
> > 65536 10.003 10.919 10.015 99.466 4.019 1591.462
> > 32768 10.117 10.124 10.169 101.018 0.229 3232.574
> > 16384 11.614 11.027 11.029 91.293 2.207 5842.771
> >
> > Unpatched, 2MB readahead, 512 max_sectors_kb
> > blocksize R R R R(avg, R(std R
> > (bytes) (s) (s) (s) MB/s) ,MB/s) (IOPS)
> > 67108864 5.268 5.316 5.418 191.996 2.241 3.000
> > 33554432 5.831 6.459 6.110 167.259 6.977 5.227
> > 16777216 7.313 7.069 7.197 142.385 1.972 8.899
> > 8388608 8.657 8.500 8.498 119.754 1.039 14.969
> > 4194304 11.846 12.116 11.801 85.911 0.994 21.478
> > 2097152 12.917 13.652 13.100 77.484 1.808 38.742
> > 1048576 9.544 10.667 10.807 99.345 5.640 99.345
> > 524288 11.736 7.171 6.599 128.410 29.539 256.821
> > 262144 7.530 7.403 7.416 137.464 1.053 549.857
> > 131072 8.741 8.002 8.022 124.256 5.029 994.051
> > 65536 10.701 10.138 10.090 99.394 2.629 1590.311
> > 32768 9.978 9.950 9.934 102.875 0.188 3291.994
> > 16384 11.435 10.823 10.907 92.684 2.234 5931.749
> >
> > Unpatched, 512KB readahead, 64 max_sectors_kb
> > blocksize R R R R(avg, R(std R
> > (bytes) (s) (s) (s) MB/s) ,MB/s) (IOPS)
> > 67108864 3.994 3.991 4.123 253.774 3.838 3.965
> > 33554432 4.100 4.329 4.161 244.111 5.569 7.628
> > 16777216 5.476 4.835 5.079 200.148 10.177 12.509
> > 8388608 5.484 5.258 5.227 192.470 4.084 24.059
> > 4194304 6.429 6.458 6.435 158.989 0.315 39.747
> > 2097152 7.219 7.744 7.306 138.081 4.187 69.040
> > 1048576 6.850 6.897 6.776 149.696 1.089 149.696
> > 524288 6.406 6.393 6.469 159.439 0.814 318.877
> > 262144 6.865 7.508 6.861 144.931 6.041 579.726
> > 131072 8.435 8.482 8.307 121.792 1.076 974.334
> > 65536 9.616 9.610 10.262 104.279 3.176 1668.462
> > 32768 9.682 9.932 10.015 103.701 1.497 3318.428
> > 16384 10.962 10.852 11.565 92.106 2.547 5894.813
> >
> > Unpatched, 2MB readahead, 64 max_sectors_kb
> > blocksize R R R R(avg, R(std R
> > (bytes) (s) (s) (s) MB/s) ,MB/s) (IOPS)
> > 67108864 3.730 3.714 3.914 270.615 6.396 4.228
> > 33554432 4.445 3.999 3.989 247.710 12.276 7.741
> > 16777216 4.763 4.712 4.709 216.590 1.122 13.537
> > 8388608 5.001 5.086 5.229 200.649 3.673 25.081
> > 4194304 6.365 6.362 6.905 156.710 5.948 39.178
> > 2097152 7.390 7.367 7.270 139.470 0.992 69.735
> > 1048576 7.038 7.050 7.090 145.052 0.456 145.052
> > 524288 6.862 7.167 7.278 144.272 3.617 288.544
> > 262144 7.266 7.313 7.265 140.635 0.436 562.540
> > 131072 8.677 8.735 8.821 117.108 0.790 936.865
> > 65536 10.865 10.040 10.038 99.418 3.658 1590.685
> > 32768 10.167 10.130 10.177 100.805 0.201 3225.749
> > 16384 11.643 11.017 11.103 91.041 2.203 5826.629
> >
> > Patched, 128KB readahead, 512 max_sectors_kb
> > blocksize R R R R(avg, R(std R
> > (bytes) (s) (s) (s) MB/s) ,MB/s) (IOPS)
> > 67108864 5.670 5.188 5.636 186.555 7.671 2.915
> > 33554432 6.069 5.971 6.141 168.992 1.954 5.281
> > 16777216 7.821 7.501 7.372 135.451 3.340 8.466
> > 8388608 9.147 8.618 9.000 114.849 2.908 14.356
> > 4194304 12.199 12.914 12.381 81.981 1.964 20.495
> > 2097152 13.449 13.891 14.288 73.842 1.828 36.921
> > 1048576 11.890 12.182 11.519 86.360 1.984 86.360
> > 524288 11.899 12.706 12.135 83.678 2.287 167.357
> > 262144 7.460 7.559 7.563 136.041 0.864 544.164
> > 131072 7.987 8.003 8.530 125.403 3.792 1003.220
> > 65536 10.179 10.119 10.131 100.957 0.255 1615.312
> > 32768 9.899 9.923 10.589 101.114 3.121 3235.656
> > 16384 10.849 10.835 10.876 94.351 0.150 6038.474
> >
> > Patched, 512KB readahead, 512 max_sectors_kb
> > blocksize R R R R(avg, R(std R
> > (bytes) (s) (s) (s) MB/s) ,MB/s) (IOPS)
> > 67108864 5.062 5.111 5.083 201.358 0.795 3.146
> > 33554432 5.589 5.713 5.657 181.165 1.625 5.661
> > 16777216 6.337 7.220 6.457 154.002 8.690 9.625
> > 8388608 7.952 7.880 7.527 131.588 3.192 16.448
> > 4194304 10.695 11.224 10.736 94.119 2.047 23.530
> > 2097152 10.898 12.072 12.358 87.215 4.839 43.607
> > 1048576 10.890 11.347 9.290 98.166 8.664 98.166
> > 524288 10.898 11.032 10.887 93.611 0.560 187.223
> > 262144 6.714 7.230 6.804 148.219 4.724 592.875
> > 131072 7.325 7.342 7.363 139.441 0.295 1115.530
> > 65536 9.773 9.988 10.592 101.327 3.417 1621.227
> > 32768 10.031 9.995 10.086 102.019 0.377 3264.620
> > 16384 11.041 10.987 11.564 91.502 2.093 5856.144
> >
> > Patched, 2MB readahead, 512 max_sectors_kb
> > blocksize R R R R(avg, R(std R
> > (bytes) (s) (s) (s) MB/s) ,MB/s) (IOPS)
> > 67108864 4.970 5.097 5.188 201.435 3.559 3.147
> > 33554432 5.588 5.793 5.169 186.042 8.923 5.814
> > 16777216 6.151 6.414 6.526 161.012 4.027 10.063
> > 8388608 7.836 7.299 7.475 135.980 3.989 16.998
> > 4194304 11.792 10.964 10.158 93.683 5.706 23.421
> > 2097152 11.225 11.492 11.357 90.162 0.866 45.081
> > 1048576 12.017 11.258 11.432 88.580 2.449 88.580
> > 524288 5.974 10.883 11.840 117.323 38.361 234.647
> > 262144 6.774 6.765 6.526 153.155 2.661 612.619
> > 131072 8.036 7.324 7.341 135.579 5.766 1084.633
> > 65536 9.964 10.595 9.999 100.608 2.806 1609.735
> > 32768 10.132 10.036 10.190 101.197 0.637 3238.308
> > 16384 11.133 11.568 11.036 91.093 1.850 5829.981
> >
> > Patched, 512KB readahead, 64 max_sectors_kb
> > blocksize R R R R(avg, R(std R
> > (bytes) (s) (s) (s) MB/s) ,MB/s) (IOPS)
> > 67108864 3.722 3.698 3.721 275.759 0.809 4.309
> > 33554432 4.058 3.849 3.957 259.063 5.580 8.096
> > 16777216 4.601 4.613 4.738 220.212 2.913 13.763
> > 8388608 5.039 5.534 5.017 197.452 8.791 24.682
> > 4194304 6.302 6.270 6.282 162.942 0.341 40.735
> > 2097152 7.314 7.302 7.069 141.700 2.233 70.850
> > 1048576 6.881 7.655 6.909 143.597 6.951 143.597
> > 524288 7.163 7.025 6.951 145.344 1.803 290.687
> > 262144 7.315 7.233 7.299 140.621 0.689 562.482
> > 131072 9.292 8.756 8.807 114.475 3.036 915.803
> > 65536 9.942 9.985 9.960 102.787 0.181 1644.598
> > 32768 10.721 10.091 10.192 99.154 2.605 3172.935
> > 16384 11.049 11.016 11.065 92.727 0.169 5934.531
> >
> > Patched, 2MB readahead, 64 max_sectors_kb
> > blocksize R R R R(avg, R(std R
> > (bytes) (s) (s) (s) MB/s) ,MB/s) (IOPS)
> > 67108864 3.697 3.819 3.741 272.931 3.661 4.265
> > 33554432 3.951 3.905 4.038 258.320 3.586 8.073
> > 16777216 5.595 5.182 4.864 197.044 11.236 12.315
> > 8388608 5.267 5.156 5.116 197.725 2.431 24.716
> > 4194304 6.411 6.335 6.290 161.389 1.267 40.347
> > 2097152 7.329 7.663 7.462 136.860 2.502 68.430
> > 1048576 7.225 7.077 7.215 142.784 1.352 142.784
> > 524288 6.903 7.015 7.095 146.210 1.647 292.419
> > 262144 7.365 7.926 7.278 136.309 5.076 545.237
> > 131072 8.796 8.819 8.814 116.233 0.130 929.862
> > 65536 9.998 10.609 9.995 100.464 2.786 1607.423
> > 32768 10.161 10.124 10.246 100.623 0.505 3219.943
> >
> > Regards,
> > Ronald.