Hi, I am getting some reject files while trying to apply "*pinunpin-cas-5.patch*" attached with the thread,
*http://www.postgresql.org/message-id/capphfdsrot1jmsnrnccqpnzeu9vut7tx6b-n1wyouwwfhd6...@mail.gmail.com <http://www.postgresql.org/message-id/capphfdsrot1jmsnrnccqpnzeu9vut7tx6b-n1wyouwwfhd6...@mail.gmail.com>* Note: I am applying this patch on top of commit " *6150a1b08a9fe7ead2b25240be46dddeae9d98e1*". With Regards, Ashutosh Sharma EnterpriseDB: http://www.enterprisedb.com On Fri, Mar 25, 2016 at 9:29 AM, Amit Kapila <amit.kapil...@gmail.com> wrote: > On Wed, Mar 23, 2016 at 1:59 PM, Ashutosh Sharma <ashu.coe...@gmail.com> > wrote: > > > > Hi All, > > > > I have been working on this issue for last few days trying to > investigate what could be the probable reasons for Performance degradation > at commit 6150a1b0. After going through Andres patch for moving buffer I/O > and content lock out of Main Tranche, the following two things come into my > > mind. > > > > 1. Content Lock is no more used as a pointer in BufferDesc structure > instead it is included as LWLock structure. This basically increases the > overall structure size from 64bytes to 80 bytes. Just to investigate on > this, I have reverted the changes related to content lock from commit > 6150a1b0 and taken at least 10 readings and with this change i can see that > the overall performance is similar to what it was observed earlier i.e. > before commit 6150a1b0. > > > > 2. Secondly, i can see that the BufferDesc structure padding is 64 bytes > however the PG CACHE LINE ALIGNMENT is 128 bytes. Also, after changing the > BufferDesc structure padding size to 128 bytes along with the changes > mentioned in above point #1, I see that the overall performance is again > similar to what is observed before commit 6150a1b0. > > > > Please have a look into the attached test report that contains the > performance test results for all the scenarios discussed above and let me > know your thoughts. > > > > So this indicates that changing back content lock as LWLock* in BufferDesc > brings back the performance which indicates that increase in BufferDesc > size to more than 64bytes on this platform has caused regression. I think > it is worth trying the patch [1] as suggested by Andres as that will reduce > the size of BufferDesc which can bring back the performance. Can you once > try the same? > > [1] - > http://www.postgresql.org/message-id/capphfdsrot1jmsnrnccqpnzeu9vut7tx6b-n1wyouwwfhd6...@mail.gmail.com > > With Regards, > Amit Kapila. > EnterpriseDB: http://www.enterprisedb.com >
