[rds-devel] Re: Fwd: Re: bcopy congestion / flow control... ?
Olaf Kirch
olaf.kirch at oracle.com
Thu Feb 7 08:30:11 PST 2008
On Thursday 07 February 2008 17:26, Olaf Kirch wrote:
> I first need to do some performance testing to
> see if they actually change anything for the better.
Here's some data with -c -t16 -d16 -q2k -T10, with and without
the congestion monitor patch. The cong_send_error is from
rds-info -c output. As you can see, the patch almost
eliminates any sendmsg() calls to a blocked destination.
With:
tsks tx/s tx+rx K/s rw+rr K/s tx us/c rtt us cpu %
16 57165 234664.50 0.00 11.03 6995.10 88.61
16 56523 231846.82 0.00 13.90 6850.03 87.06
16 57329 235077.69 0.00 14.26 6928.14 88.27
16 56644 232725.80 0.00 13.27 6818.35 87.93
16 53708 220394.22 0.00 9.75 7566.85 85.12
16 56534 232124.08 0.00 13.29 7115.16 89.74
16 56458 231775.76 0.00 10.97 6992.60 88.61
16 62094 234593.76 0.00 11.94 6055.03 78.22
16 55710 228850.61 0.00 12.59 7343.49 90.86
16 40387 165520.50 0.00 15.24 6901.72 74.94
---------------------------------------------
16 54709 224838.12 0.00 12.69 7013.30 85.87 (average)
cong_send_error 61
Without:
16 53084 215330.30 0.00 12.05 17275.83 98.30
16 52496 214284.69 0.00 10.97 16090.59 97.98
16 52836 215839.99 0.00 10.84 15903.95 96.14
16 52780 215447.82 0.00 17.88 13803.93 96.02
16 54858 223465.00 0.00 10.77 13802.60 95.04
16 53378 218084.21 0.00 10.22 14450.08 94.39
16 52483 213937.36 0.00 10.67 13866.91 95.70
16 53911 220019.19 0.00 10.65 14293.49 95.03
16 54424 222617.79 0.00 15.82 13304.42 93.24
16 46905 191467.42 0.00 13.78 13508.08 88.06
---------------------------------------------
16 52655 215050.01 0.00 12.36 14652.36 94.99 (average)
cong_send_error 1359177
Performance doesn't change a lot, which is kind of expected,
but RTT and CPU utilization improve noticeably.
At 10 microseconds per sendmsg call, cutting out 1.3 million
sendmsg calls amounts to 13 seconds of CPU time.
Olaf
--
Olaf Kirch | --- o --- Nous sommes du soleil we love when we play
okir at lst.de | / | \ sol.dhoop.naytheet.ah kin.ir.samse.qurax
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