Re: Move PinBuffer and UnpinBuffer to atomics

On Sun, Apr 3, 2016 at 2:28 PM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:

>
> What is the conclusion of this test? As far as I see, with the patch
> (0001-WIP-Avoid-the-use-of-a-separate-spinlock-to-protect), the performance
> degradation is not fixed, but with pin-unpin patch, the performance seems
> to be better in most of the runs, however still you see less performance in
> some of the runs. Is that right?
>

Summary Of the Run:
-----------------------------
1. Throughout one run if we observe TPS every 30 seconds its stable in one
run.
2. With Head 64 client run vary between ~250,000 to ~450000. you can see
below results.

run1: 434860 (5min)
run2: 275815 (5min)
run3: 437872 (5min)
run4: 237033 (5min)
run5: 347611 (10min)
run6: 435933 (20min)

3. With Head + 0001-WIP-Avoid-the-use-of-a-separate-spinlock-to-protect
with 64 client I always saw ~450,000 TPS

run1: 429520 (5min)
run2: 446249 (5min)
run3: 431066 (5min)
run4: 441280 (10min)
run5: 429844 (20 mins)

4. With Head+ 0001-WIP-Avoid-the-use-of-a-separate-spinlock-to-protect
with 128 Client something performance is as low as ~150,000 which is never
observed with Head (with head it is constantly ~ 350,000 TPS).

run1: 372958 (5min)
run2: 167189 (5min)
run3: 381592 (5min)
run4: 441280 (10min)
run5: 362742 (20 min)

5. With Head+pinunpin-cas-8, with 64 client its ~ 550,000 TPS and with 128
client ~650,000 TPS.

6. With Head+ pinunpin-cas-8 +
0001-WIP-Avoid-the-use-of-a-separate-spinlock-to-protect performance is
almost same as with
Head+pinunpin-cas-8, only sometime performance at 128 client is low
(~250,000 instead of 650,000)

Seems like Head+ pinunpin-cas-8 is giving best performance and without much
fluctuation.

> Can you answer some of the questions asked by Andres upthread[1]?
>
>
> [1] -
> http://www.postgresql.org/message-id/20160401083518.GE9074@awork2.anarazel.de
>

Non Default Parameter:
--------------------------------
shared_buffer 8GB
Max Connections 150

./pgbench -c $threads -j $threads -T 1200 -M prepared -S -P 30 postgres

*BufferDesc Size:*
*------------------------*
Head: 80 Bytes
Head+0001-WIP-Avoid-the-use-of-a-separate-spinlock-to-protect : 72Bytes
Head+0001-WIP-Avoid-the-use-of-a-separate-spinlock-to-protect+
Pinunpin-cas-8 : 64 Bytes

--
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com