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 <[email protected]> schrieb am 22.04.2015 um 23:18 >>>>>> in Nachricht >>> <[email protected]>: >>> >>> [...] >>>> Free stats look fine to me. No swap is being used, or has been used >>>> yet >>>> on this system. >>>> >>>> total used free shared buffers >>>> cached >>>> 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. > > http://www.atoptool.nl/ > > 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
