05.02.2017 22:05, I wrote:
[...]
And yes, running Process Explorer gave some new and unexpected input.
During the period of this strange high load it claims 40% CPU is used by
interrupts (normally 0.01%) and 3% used by backend postgres.exe
(normally approx 0%). I'd guess this means some problem happening in the
OS (which hosts this postgres.exe), probably related to network
communication? (Because nothing else seems likely related to interrupts
in such scenario?)
Ok, I've got a working example as simple as the following:
do {
for (i=0; i<40; i++) {
Sleep(15);
res = PQexec(conn, "SELECT localtimestamp ");
if (PQresultStatus(res) != PGRES_TUPLES_OK) return 1;
PQclear(res);
}
fprintf(stdout, "*");
Sleep(350);
} while(1);
Here, Sleep(15) and Sleep(350) are very important, removing or changing
them can cause the effect to disappear.
Looks like some timing-sensitive issue in windows TCP/IP implementation?
But then, how can it be that no-one have noticed it yet? Puzzling.
Thank you.
Regards,
Nikolai
Additionally, I've now got a kernrate viewer reports, one for high load,
and one for normal load period, attached below. Here, tcpip shows some
more kernel activity during the problematic period, but the difference
is not so huge.
Time 36348 hits, 25000 events per hit --------
Module Hits msec %Total Events/Sec
intelppm 35048 45640 96 % 19198071
hal 1030 45640 2 % 564198
ntkrnlpa 204 45640 0 % 111744
tcpip 20 45640 0 % 10955
win32k 18 45640 0 % 9859
afd 6 45640 0 % 3286
ipnat 6 45640 0 % 3286
NDIS 4 45640 0 % 2191
......
Time 37227 hits, 25000 events per hit --------
Module Hits msec %Total Events/Sec
intelppm 35856 46828 96 % 19142393
hal 1089 46828 2 % 581382
ntkrnlpa 229 46828 0 % 122255
win32k 29 46828 0 % 15482
tcpip 9 46828 0 % 4804
NDIS 4 46828 0 % 2135
afd 3 46828 0 % 1601
psched 3 46828 0 % 1601
ipnat 2 46828 0 % 1067
Thank you.
Nikolai
The screenshot: https://yadi.sk/i/hC8FMZCE3CyzPs
Thank you.
Nikolai
Andres
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