On the record the IBM kernel architects state smt8 is not an issue with
anything, off the record they agree that smtX and the Informix internal
thread scheduling don't play nicely together
Cheers
Paul
> Hi SangGyu,
>
>
> I would try setting smt back to 4. I have observed that increasing smt to
> more than 4 rarely provides better performance, and often decreased
> performance.
> I was going to explain that phenomenon, but just reading Art's email that
> explains it perfectly: in short, raising smt gives you less power Playing
> with smt with high values is not good for Informix at least with current
> versions of AIX??????
>
> BR
> Eric
>
>
>
> -------------------------------------------
> Original Message:
> Sent: 10/13/2020 11:08:00 PM
> From: SangGyu Jeong
> Subject: long checkpoint
>
> My customer changed the server a few days ago and modified the Informix
> onconfig parameters vpclass and cleaners.
> Perhaps because of that, the checkpoint duration has increased to around
> 30 seconds. Before, it usually took 1 or 2 seconds.
> Is the parameter change related to the checkpoint duration?
>
> -CPU core information and parameter values of old server
> AIX 7.1(E850), 4 core, smt4
> CLEANERS 12
> VPCLASS cpu,num=10,noage
>
> -CPU core information and parameter values of new server
> AIX 7.1(E950), 4 core, smt8
> CLEANERS 20
> VPCLASS cpu,num=20,noage
>
>
> Below is the result of onstat -g ckp on the current server.
>
> IBM Informix Dynamic Server Version 11.70.FC9 -- On-Line -- Up 4 days
> 05:46:44 -- 46601584 Kbytes
>
> AUTO_CKPTS=On RTO_SERVER_RESTART=Off
>
> Critical
> Sections
>
>
>
>
> Physical
> Log
> Logical
> Log
> Clock Total Flush Block #
> Ckpt Wait Long # Dirty Dskflu Total Avg Total
> Avg
> Interval Time Trigger LSN Time Time Time Waits
> Time Time Time Buffers /Sec Pages /Sec Pages /Sec
> 1065136 10:48:40 HA 175881:0x488d878 1.5 1.5 0.0 3
> 0.0 0.0 0.0 18366 12564 50016 806 24469 394
> 1065137 10:49:42 HA 175882:0x5cae040 3.8 3.5 0.0 7
> 0.2 0.2 0.3 23897 6876 46506 762 30315 496
> 1065138 10:51:21 HA 175883:0x17c95a8 34.9 34.9 0.0 1
> 0.0 0.0 0.0 16901 484 85227 1272 13462 200
> 1065139 10:52:26 HA 175883:0x354c018 34.9 34.8 0.0 1
> 0.0 0.0 0.0 17433 500 86972 1338 8530 131
> 1065140 10:57:01 CKPTINTVL 175884:0x120018 8.6 8.5 0.0 1
> 0.0 0.0 0.0 16721 1965 3485 11 11921 39
> 1065141 11:02:37 CKPTINTVL 175884:0x54f4018 35.0 35.0 0.0 0
> 0.0 0.0 0.0 17636 503 4084 13 22435 72
> 1065142 11:08:51 CKPTINTVL 175885:0x24c4018 104.3 104.1 0.0 14
> 0.0 0.0 0.0 19202 184 4966 16 17400 57
> 1065143 11:10:01 HA 175885:0x374e018 69.9 69.8 0.0 5
> 0.0 0.0 0.0 21778 312 3414 32 7329 70
> 1065144 11:11:11 HA 175885:0x4185018 69.8 69.7 0.0 14
> 0.0 0.1 0.1 20655 296 2217 31 4522 64
> 1065145 11:11:47 HA 175885:0x4933018 35.8 35.6 0.0 65
> 0.1 0.1 0.2 16512 463 2261 32 2549 36
> 1065146 11:17:13 CKPTINTVL 175886:0x1e49058 59.3 36.2 0.0 313
> 23.0 13.0 23.0 22340 617 6231 19 14668 44
> 1065147 11:22:53 CKPTINTVL 175886:0x4cc1018 70.3 70.2 0.0 1
> 0.0 0.0 0.0 21282 303 5921 19 14930 48
> 1065148 11:23:29 HA 175886:0x58d7018 34.9 34.9 0.0 0
> 0.0 0.0 0.0 19559 560 2349 33 5360 75
> 1065149 11:28:31 CKPTINTVL 175887:0x2b1d018 34.8 34.7 0.0 0
> 0.0 0.0 0.0 18766 540 5537 18 14646 48
> 1065150 11:33:37 CKPTINTVL 175887:0x517e018 35.9 35.9 0.0 2
> 0.0 0.0 0.0 22631 630 4347 14 12552 41
> 1065151 11:38:43 CKPTINTVL 175888:0x206c018 36.3 36.2 0.0 1
> 0.0 0.0 0.0 17839 492 4411 14 13636 44
> 1065152 11:43:49 CKPTINTVL 175888:0x3e34018 36.7 36.6 0.0 2
> 0.0 0.0 0.0 23057 630 3415 11 8323 27
> 1065153 11:48:31 CKPTINTVL 175888:0x60cc018 12.6 12.5 0.0 1
> 0.0 0.0 0.0 20291 1618 3290 10 9044 29
> 1065154 11:54:32 CKPTINTVL 175889:0x12a3018 61.6 61.6 0.0 0
> 0.0 0.0 0.0 13622 221 2107 6 7364 23
> 1065155 11:54:34 HA 175889:0x1bef810 1.0 1.0 0.0 1
> 0.0 0.0 0.0 8194 8194 734 11 2386 38
>
> Max Plog Max Llog Max Dskflush Avg Dskflush Avg Dirty
> Blocked
> pages/sec pages/sec Time pages/sec pages/sec
> Time
> 8692 4715 391 1195 0
> 0???
>
>
>
>
> ------------------------------
> SangGyu Jeong
> Software Engineer
> Infrasoft
> Seoul Korea, Republic of
> ------------------------------
>
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Original Message:
Sent: 10/14/2020 1:28:00 AM
From: Eric Vercelletto
Subject: RE: long checkpoint
Hi SangGyu,
I would try setting smt back to 4. I have observed that increasing smt to more than 4 rarely provides better performance, and often decreased performance.
I was going to explain that phenomenon, but just reading Art's email that explains it perfectly: in short, raising smt gives you less power Playing with smt with high values is not good for Informix at least with current versions of AIX��
BR
Eric
Original Message:
Sent: 10/13/2020 11:08:00 PM
From: SangGyu Jeong
Subject: long checkpoint
My customer changed the server a few days ago and modified the Informix onconfig parameters vpclass and cleaners.
Perhaps because of that, the checkpoint duration has increased to around 30 seconds. Before, it usually took 1 or 2 seconds.
Is the parameter change related to the checkpoint duration?
-CPU core information and parameter values of old server
AIX 7.1(E850), 4 core, smt4
CLEANERS 12
VPCLASS cpu,num=10,noage
-CPU core information and parameter values of new server
AIX 7.1(E950), 4 core, smt8
CLEANERS 20
VPCLASS cpu,num=20,noage
Below is the result of onstat -g ckp on the current server.
IBM Informix Dynamic Server Version 11.70.FC9 -- On-Line -- Up 4 days 05:46:44 -- 46601584 Kbytes
AUTO_CKPTS=On RTO_SERVER_RESTART=Off
Critical Sections Physical Log Logical Log
Clock Total Flush Block # Ckpt Wait Long # Dirty Dskflu Total Avg Total Avg
Interval Time Trigger LSN Time Time Time Waits Time Time Time Buffers /Sec Pages /Sec Pages /Sec
1065136 10:48:40 HA 175881:0x488d878 1.5 1.5 0.0 3 0.0 0.0 0.0 18366 12564 50016 806 24469 394
1065137 10:49:42 HA 175882:0x5cae040 3.8 3.5 0.0 7 0.2 0.2 0.3 23897 6876 46506 762 30315 496
1065138 10:51:21 HA 175883:0x17c95a8 34.9 34.9 0.0 1 0.0 0.0 0.0 16901 484 85227 1272 13462 200
1065139 10:52:26 HA 175883:0x354c018 34.9 34.8 0.0 1 0.0 0.0 0.0 17433 500 86972 1338 8530 131
1065140 10:57:01 CKPTINTVL 175884:0x120018 8.6 8.5 0.0 1 0.0 0.0 0.0 16721 1965 3485 11 11921 39
1065141 11:02:37 CKPTINTVL 175884:0x54f4018 35.0 35.0 0.0 0 0.0 0.0 0.0 17636 503 4084 13 22435 72
1065142 11:08:51 CKPTINTVL 175885:0x24c4018 104.3 104.1 0.0 14 0.0 0.0 0.0 19202 184 4966 16 17400 57
1065143 11:10:01 HA 175885:0x374e018 69.9 69.8 0.0 5 0.0 0.0 0.0 21778 312 3414 32 7329 70
1065144 11:11:11 HA 175885:0x4185018 69.8 69.7 0.0 14 0.0 0.1 0.1 20655 296 2217 31 4522 64
1065145 11:11:47 HA 175885:0x4933018 35.8 35.6 0.0 65 0.1 0.1 0.2 16512 463 2261 32 2549 36
1065146 11:17:13 CKPTINTVL 175886:0x1e49058 59.3 36.2 0.0 313 23.0 13.0 23.0 22340 617 6231 19 14668 44
1065147 11:22:53 CKPTINTVL 175886:0x4cc1018 70.3 70.2 0.0 1 0.0 0.0 0.0 21282 303 5921 19 14930 48
1065148 11:23:29 HA 175886:0x58d7018 34.9 34.9 0.0 0 0.0 0.0 0.0 19559 560 2349 33 5360 75
1065149 11:28:31 CKPTINTVL 175887:0x2b1d018 34.8 34.7 0.0 0 0.0 0.0 0.0 18766 540 5537 18 14646 48
1065150 11:33:37 CKPTINTVL 175887:0x517e018 35.9 35.9 0.0 2 0.0 0.0 0.0 22631 630 4347 14 12552 41
1065151 11:38:43 CKPTINTVL 175888:0x206c018 36.3 36.2 0.0 1 0.0 0.0 0.0 17839 492 4411 14 13636 44
1065152 11:43:49 CKPTINTVL 175888:0x3e34018 36.7 36.6 0.0 2 0.0 0.0 0.0 23057 630 3415 11 8323 27
1065153 11:48:31 CKPTINTVL 175888:0x60cc018 12.6 12.5 0.0 1 0.0 0.0 0.0 20291 1618 3290 10 9044 29
1065154 11:54:32 CKPTINTVL 175889:0x12a3018 61.6 61.6 0.0 0 0.0 0.0 0.0 13622 221 2107 6 7364 23
1065155 11:54:34 HA 175889:0x1bef810 1.0 1.0 0.0 1 0.0 0.0 0.0 8194 8194 734 11 2386 38
Max Plog Max Llog Max Dskflush Avg Dskflush Avg Dirty Blocked
pages/sec pages/sec Time pages/sec pages/sec Time
8692 4715 391 1195 0 0
------------------------------
SangGyu Jeong
Software Engineer
Infrasoft
Seoul Korea, Republic of
------------------------------
#Informix