On 2015-04-23 4:43 PM, Howard Chu wrote:
Geoff Swan wrote:
On 2015-04-23 4:07 PM, Ulrich Windl wrote:
Geoff Swan gswan3@bigpond.net.au schrieb am 22.04.2015 um 23:18 in Nachricht
5538100A.3060301@bigpond.net.au:
[...]
Free stats look fine to me. No swap is being used, or has been used yet on this system.
total used free shared bufferscached Mem: 132005400 21928192 110077208 10612 363064 19230072 -/+ buffers/cache: 2335056 129670344 Swap: 8388604 0 8388604
The effect I am seeing is that despite a reasonably fast disc system, the kernel writing of dirty pages is painfully slow.
So disk I/O stats is also available via sar. May we see them? Finally there's blktrace where you can follow the timing and positions of each individual block being written, but that's not quite easy to run and analyze (unless I missed the easy way).
I suspect scattered writes that bring your I/O rate down.
Regards, Ulrich
sysstat (and sar) is not installed on this system, so I can't give you that output.
As I said in my previous email - use iostat and/or vmstat to monitor paging activity and system wait time. You can also install atop and get all of the relevant stats on one screen.
I find it indispensible these days.
Thanks, I'll look at buiding it. I have used nmon for a while to view cpu/vm/mem/diskio stats at once.
The system is very lightly loaded at the moment.
# vmstat -w 2 10 procs ---------------memory-------------- ---swap-- -----io---- -system-- ------cpu----- r b swpd free buff cache si so bi bo in cs us sy id wa st 0 1 0 109758112 391744 19534916 0 0 3 25 3 2 2 0 97 1 0 0 0 0 109758304 391752 19534920 0 0 0 1160 1852 1360 1 0 97 2 0 1 1 0 109755448 391752 19534924 0 0 0 622 1899 1244 1 0 97 1 0 0 1 0 109755536 391752 19534928 0 0 0 2444 1917 1427 1 0 97 2 0 1 1 0 109756784 391756 19534940 0 0 0 116 4987 2658 3 1 96 1 0 3 1 0 109755440 391756 19534948 0 0 0 396 6009 3341 3 2 94 2 0 1 1 0 109756176 391760 19534964 0 0 0 306 6312 3260 3 2 94 1 0 0 1 0 109757840 391760 19534976 0 0 0 320 6120 3293 3 2 94 1 0 0 1 0 109755968 391760 19534984 0 0 0 222 4617 2569 2 1 96 1 0 1 1 0 109754528 391760 19534988 0 0 0 256 2002 1434 1 0 98 1 0