Before I start diving into the code, has anybody else out there had problems with 'fio' not being able to scale well with large numbers of devices (files) being used? I have a system w/ 32-cpus, 256GB RAM, plus 11 dual-ported FC HBAs connected to 44 HP MSA1000 FC controllers. (the 44 MSAs are spread out 4 per FC HBA). I'd like to use 'fio' to gather & produce scaling results, but I seem to run into inconsistencies once I get above using 26 or 27 of the 44 MSAs. I have noticed similar things in the past, but it hasn't been so bothersome. I have a locally crafted tool (much more limited than 'fio') called 'aiod' that /is/ able to scale up past 35 or 36 of the MSAs doing what I /believe/ is something similar. [Once past 35 or 36 devices we run into system issues which reduce scaling opportunities.] In any event, an example fio job-file can be found at: http://free.linux.hp.com/~adb/2009-08-17/044_disk_1_parts.txt The graph showing the noise in the graph for fio can be found at: http://free.linux.hp.com/~adb/2009-08-17/fio.png And the "better" graph w/ aiod can be found at: http://free.linux.hp.com/~adb/2009-08-17/aiod.png The test uses between 1 and 4 partitions per LUN exported by each MSA (each LUN is crafted from 4 physical devices striped together.) You'll see in the latter graph the continued scaling up through almost 37 devices, and much tighter results after that (even with the tail-off at the end above 40 devices.) Anyways, if there is something I'm missing in the fio job-file to help it scale better let me know, otherwise I'll go through the aiod code to see if there were any applicable scaling improvements there than can be applied to fio... Alan D. Brunelle Hewlett-Packard -- To unsubscribe from this list: send the line "unsubscribe fio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
