The function disksize() reports disks smaller than 64 GiB as zero size. A later algorithm subtracts a "buffer" value from this to obtain an intermediate value, and later parts of the program assume this intermediate value is positive. I be Reproducible: Always Steps to Reproduce: 1. Obtain 32 GB storage media as /dev/sdb 2. piozone -v /dev/sdb Actual Results: occam ~ # piozone /dev/sdb [PIOZONE, version 1.0 - Copyright (c) 2002 Peter Eriksson <pen@lysator.liu.se>] Linear read transfer rates: 26.6 MB/s at offset 0 GB using 64 KiB reads 27.1 MB/s at offset 633437444 GB using 64 KiB reads 27.5 MB/s at offset 1266874888 GB using 64 KiB reads 27.1 MB/s at offset 633437443 GB using 64 KiB reads 26.9 MB/s at offset 1266874887 GB using 64 KiB reads 26.8 MB/s at offset 633437442 GB using 64 KiB reads 26.8 MB/s at offset 1266874886 GB using 64 KiB reads 26.9 MB/s at offset 633437441 GB using 64 KiB reads 26.9 MB/s at offset 1266874885 GB using 64 KiB reads 27.2 MB/s at offset 633437440 GB using 64 KiB reads 27.2 MB/s at offset 1266874884 GB using 64 KiB reads 27.1 MB/s at offset 633437438 GB using 64 KiB reads 27.4 MB/s at offset 1266874883 GB using 64 KiB reads 27.1 MB/s at offset 633437437 GB using 64 KiB reads 26.8 MB/s at offset 1266874882 GB using 64 KiB reads 26.8 MB/s at offset 633437436 GB using 64 KiB reads 27.2 MB/s at offset 1266874881 GB using 64 KiB reads 27.2 MB/s at offset 633437435 GB using 64 KiB reads 27.3 MB/s at offset 1266874880 GB using 64 KiB reads 26.9 MB/s at offset 633437434 GB using 64 KiB reads 27.1 MB/s at offset 1266874878 GB using 64 KiB reads 26.8 MB/s at offset 633437433 GB using 64 KiB reads 26.9 MB/s at offset 1266874877 GB using 64 KiB reads 26.9 MB/s at offset 633437432 GB using 64 KiB reads 26.9 MB/s at offset 1266874876 GB using 64 KiB reads 27.2 MB/s at offset 633437431 GB using 64 KiB reads 28.0 MB/s at offset 1266874875 GB using 64 KiB reads 28.0 MB/s at offset 633437430 GB using 64 KiB reads 28.2 MB/s at offset 1266874874 GB using 64 KiB reads 28.2 MB/s at offset 633437429 GB using 64 KiB reads 28.1 MB/s at offset 1266874873 GB using 64 KiB reads 28.3 MB/s at offset 633437428 GB using 64 KiB reads 27.8 MB/s at offset 1266874872 GB using 64 KiB reads 27.9 MB/s at offset 633437427 GB using 64 KiB reads 27.9 MB/s at offset 1266874871 GB using 64 KiB reads 28.1 MB/s at offset 633437426 GB using 64 KiB reads 28.0 MB/s at offset 1266874870 GB using 64 KiB reads 27.9 MB/s at offset 0 GB using 1024 KiB reads 27.9 MB/s at offset 633437444 GB using 1024 KiB reads 28.1 MB/s at offset 1266874888 GB using 1024 KiB reads 28.2 MB/s at offset 633437443 GB using 1024 KiB reads 28.3 MB/s at offset 1266874887 GB using 1024 KiB reads 28.2 MB/s at offset 633437442 GB using 1024 KiB reads 27.8 MB/s at offset 1266874886 GB using 1024 KiB reads 28.2 MB/s at offset 633437441 GB using 1024 KiB reads 28.3 MB/s at offset 1266874885 GB using 1024 KiB reads 36.5 MB/s at offset 633437440 GB using 1024 KiB reads 30.4 MB/s at offset 1266874884 GB using 1024 KiB reads 28.1 MB/s at offset 633437438 GB using 1024 KiB reads 27.2 MB/s at offset 1266874883 GB using 1024 KiB reads 26.9 MB/s at offset 633437437 GB using 1024 KiB reads 28.2 MB/s at offset 1266874882 GB using 1024 KiB reads 32.1 MB/s at offset 633437436 GB using 1024 KiB reads 29.9 MB/s at offset 1266874881 GB using 1024 KiB reads 27.4 MB/s at offset 633437435 GB using 1024 KiB reads 27.1 MB/s at offset 1266874880 GB using 1024 KiB reads 27.3 MB/s at offset 633437434 GB using 1024 KiB reads 26.9 MB/s at offset 1266874878 GB using 1024 KiB reads 26.9 MB/s at offset 633437433 GB using 1024 KiB reads 29.5 MB/s at offset 1266874877 GB using 1024 KiB reads 27.2 MB/s at offset 633437432 GB using 1024 KiB reads 27.0 MB/s at offset 1266874876 GB using 1024 KiB reads 28.6 MB/s at offset 633437431 GB using 1024 KiB reads 28.1 MB/s at offset 1266874875 GB using 1024 KiB reads 26.9 MB/s at offset 633437430 GB using 1024 KiB reads 26.9 MB/s at offset 1266874874 GB using 1024 KiB reads 26.8 MB/s at offset 633437429 GB using 1024 KiB reads 26.8 MB/s at offset 1266874873 GB using 1024 KiB reads 29.3 MB/s at offset 633437428 GB using 1024 KiB reads 26.8 MB/s at offset 1266874872 GB using 1024 KiB reads 26.9 MB/s at offset 633437427 GB using 1024 KiB reads 30.9 MB/s at offset 1266874871 GB using 1024 KiB reads Random access read transfer rates (area size: 1 GiB): 7994.8 MB/s at offset 0 GB using 64 KiB reads 65.0 MB/s at offset 0 GB using 1024 KiB reads Expected Results: occam ~ # ~eroen/repos/piozone/piozone -v /dev/sdb [PIOZONE, version 1.0 - Copyright (c) 2002 Peter Eriksson <pen@lysator.liu.se>] Disk size: 32 GB (29 GiB) Linear read transfer rates: 20.3 MB/s at offset 0 GB using 64 KiB reads 20.3 MB/s at offset 15 GB using 64 KiB reads 20.5 MB/s at offset 30 GB using 64 KiB reads 40.7 MB/s at offset 0 GB using 1024 KiB reads 40.7 MB/s at offset 15 GB using 1024 KiB reads Random access read transfer rates (area size: 1 GiB): 8444.3 MB/s at offset 0 GB using 64 KiB reads 8878.6 MB/s at offset 15 GB using 64 KiB reads 8952.0 MB/s at offset 30 GB using 64 KiB reads 7855.2 MB/s at offset 0 GB using 1024 KiB reads 8144.7 MB/s at offset 15 GB using 1024 KiB reads 8254.3 MB/s at offset 30 GB using 1024 KiB reads The problematic piece of code: uint64_t disksize(int fd) { char buf[8*KiB]; uint64_t off, del; off = 0; del = 64*GiB; while (del > 8*KiB && lseek64(fd, off+del, SEEK_SET) != -1) { if (read(fd, buf, 8*KiB) < 0) del >>= 1; else off += del; } return off; }
Created attachment 378748 [details, diff] fix-disksize-determination.patch Please find attached a proposed patch to rectify this issue.
Created attachment 378768 [details, diff] 02-use-o_direct-to-reduce-cache.patch I also ran into a few other issues with piozone, for which I will attach proposed patches. You will see in Comment 0 that (in particular) the random reads are highly inflated due to caching. With this patch, the device under test is opened with O_DIRECT where available, which reduces the impact of caching on the results.
Created attachment 378770 [details, diff] 03-bench_linear-should-fail-if.patch In the existing bench_linear(), errors from seeking to invalid offsets is silently ignored, which causes re-testing of the same area (and incorrect output) rather than progression though the program.
Tangentially related, but LICENSE="GPL-2" seems wrong. The source has no mention of gpl, but rather this statement: ** Copyright (c) 2002 Peter Eriksson <pen@lysator.liu.se> ** ** This program is free software; you can redistribute it and/or ** modify it as you wish - as long as you don't claim that you wrote ** it. ** ** This program is distributed in the hope that it will be useful, ** but WITHOUT ANY WARRANTY; without even the implied warranty of ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
Are you willing to proxy maintain this old package? Otherwise I don't see much sense on trying to keep this software from 2002 in the tree (as we will likely be unable to fix the bugs that will probably arise as soon as someone tries to rely on it extensively )
removed
