Dear All, for some time we see ~20% regression in reread operation in iozone data. Kernel 4.6.0-1 was OK, but since that, there is ~20% regression from 1MB file size on SATA SSD disks and also similar one on SAS HDD, as you can see here: https://bugzilla.kernel.org/show_bug.cgi?id=155821 links to some plots: SAS HDD: https://bugzilla.kernel.org/attachment.cgi?id=242491 SATA SSD: https://bugzilla.kernel.org/attachment.cgi?id=242501 The plots are for the XFS file system, but it looks very similar for the Ext4. The machine which I used for the generating these plots is 2 NUMA, 32GB RAM Lenovo x3550 M5 I used numactl to pin iozone only to socket 0. We see this also on different machines. Can you help us to find the cause of this regression? Do you have any idea why it is only in reread? Data from the results, showing percentage difference between 4.6 and 4.7 kernels for various file size. SATA SSD drive, iozone re-read operation File size [MB] | kernel 4.6 [MB] | err [%] | kernel 4.7 [MB] | err [%] | difference [%] ---------------------------------------------------------------------------------------- 1.0 | 13269.10 | 5.0 | 10416.83 | 1.9 | -21.5 2.0 | 13015.61 | 4.7 | 10024.62 | 0.2 | -23.0 4.0 | 12745.33 | 4.5 | 10050.46 | 0.2 | -21.1 8.0 | 12905.56 | 3.1 | 9934.37 | 1.4 | -23.0 16.0 | 11294.55 | 6.7 | 9627.13 | 0.0 | -14.8 32.0 | 7417.55 | 4.8 | 6454.81 | 1.8 | -13.0 64.0 | 6789.36 | 3.6 | 5759.64 | 2.0 | -15.2 128.0 | 6768.6 | 0.8 | 5930.25 | 1.7 | -12.4 256.0 | 7199.7 | 0.0 | 6101.62 | 0.7 | -15.2 512.0 | 7456.02 | 0.1 | 6234.62 | 0.4 | -16.4 1024.0 | 7503.09 | 0.4 | 6230.33 | 0.2 | -17.0 2048.0 | 7509.11 | 0.4 | 6177.36 | 0.1 | -17.7 4096.0 | 7486.92 | 0.1 | 6219.58 | 0.5 | -16.9 8192.0 | 6860.39 | 0.0 | 5760.61 | 0.3 | -16.0 16384.0 | 6702.57 | 0.1 | 5624.17 | 0.1 | -16.1 32768.0 | 1215.87 | 0.8 | 942.31 |12.8 | -22.5 65536.0 | 511.72 | 0.2 | 512.58 | 0.2 | 0.2 SATA SSD drive, iozone re-read operation File size [MB] | kernel 4.6 [MB] | err [%] | kernel 4.7 [MB] | err [%] | difference [%] ---------------------------------------------------------------------------------------- 1.0 | 9281.34 | 29.5 | 9949.28 | 2.3 | 7.2 2.0 | 8245.63 | 25.0 | 9732.59 | 2.1 | 18.0 4.0 | 10183.30 | 2.7 | 9454.31 | 1.2 | -7.2 8.0 | 10329.19 | 11.3 | 9093.59 | 4.7 | -12.0 16.0 | 10356.85 | 11.1 | 8913.64 | 2.5 | -13.9 32.0 | 7495.62 | 5.6 | 6217.42 | 2.4 | -17.1 64.0 | 6608.68 | 7.6 | 5749.62 | 2.1 | -13.0 128.0 | 7012.76 | 5.0 | 5927.56 | 1.1 | -15.5 256.0 | 7203.37 | 1.7 | 6130.53 | 0.9 | -14.9 512.0 | 7429.33 | 0.5 | 6219.21 | 0.4 | -16.3 1024.0 | 7470.16 | 0.4 | 6247.00 | 0.3 | -16.4 2048.0 | 7468.32 | 0.2 | 6209.81 | 0.8 | -16.9 4096.0 | 7475.38 | 0.1 | 6065.46 | 1.8 | -18.9 8192.0 | 6854.90 | 0.3 | 5687.97 | 0.2 | -17.0 16384.0 | 6678.79 | 0.3 | 5594.29 | 0.4 | -16.2 32768.0 | 444.30 | 0.7 | 483.13 |10.3 | 8.7 65536.0 | 304.49 | 0.0 | 250.57 | 0.0 | -17.7 Thanks in advance for any informations or suggestions. Best Regards Matus Kocka -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
