From: Bruce Momjian <bruce@momjian.us>
To: Tels <nospam-pg-abuse@bloodgate.com>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: Andres Freund <andres@anarazel.de>
Cc: Amit Kapila <amit.kapila16@gmail.com>
Cc: Rafia Sabih <rafia.sabih@enterprisedb.com>
Cc: PostgreSQL Developers <pgsql-hackers@postgresql.org>
Subject: Re: [HACKERS] [POC] Faster processing at Gather node
Date: Thu, 29 Mar 2018 12:18:43 -0400
Message-ID: <20180329161843.GC16165@momjian.us> (raw)
In-Reply-To: <e66e05bc55f5ce904e361ad17a3395ae.squirrel@sm.webmail.pair.com>
References: <CAA4eK1LSDydwrNjmYSNkfJ3ZivGSWH9SVswh6QpNzsMdj_oOQA@mail.gmail.com>
<CA+TgmobL3rzeo7XrYbat4FHR=L9+ZA4ZmzjxCvTwa-NBR=O_Sw@mail.gmail.com>
<20180110000934.lft7ebeqek4grrlx@alap3.anarazel.de>
<CA+Tgmob=kOVeaw3v-OCRPbmtK1qHhu3uvHV6ANxoB2xZuir_=Q@mail.gmail.com>
<20180207184137.5mv4bipj3t7hbncv@alap3.anarazel.de>
<CA+TgmobkN-g10qNU4-qPApAPG9w7euFJgU1Y-TGtXr9TUeZ3=w@mail.gmail.com>
<20180227210638.caug5j5po4xk5ktf@alap3.anarazel.de>
<CA+Tgmob2c7LVijbpWoMOBvxkZjaJ_E7ZesKKJoHTfAL1B1PYag@mail.gmail.com>
<CA+TgmoZG_6PK5F7jd9rv0P5u4bweLm4X=3oYq5P5iYwtdtikEw@mail.gmail.com>
<e66e05bc55f5ce904e361ad17a3395ae.squirrel@sm.webmail.pair.com>
On Fri, Mar 2, 2018 at 05:21:28PM -0500, Tels wrote:
> Hello Robert,
>
> On Fri, March 2, 2018 12:22 pm, Robert Haas wrote:
> > On Wed, Feb 28, 2018 at 10:06 AM, Robert Haas <robertmhaas@gmail.com>
> > wrote:
> >> [ latest patches ]
> >
> > Committed. Thanks for the review.
>
> Cool :)
>
> There is a typo, tho:
>
> + /*
> + * If the counterpary is known to have attached, we can read mq_receiver
> + * without acquiring the spinlock and assume it isn't NULL. Otherwise,
> + * more caution is needed.
> + */
>
> s/counterpary/counterparty/;
>
> Sorry, only noticed while re-reading the thread.
>
> Also, either a double space is missing, or one is too many:
>
> + /*
> + * Separate prior reads of mq_ring from the increment of mq_bytes_read
> + * which follows. Pairs with the full barrier in shm_mq_send_bytes(). We
> + * only need a read barrier here because the increment of mq_bytes_read is
> + * actually a read followed by a dependent write.
> + */
>
> (" Pairs ..." vs. ". We only ...")
>
> Best regards,
Change applied with the attached patch.
--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ As you are, so once was I. As I am, so you will be. +
+ Ancient Roman grave inscription +
Attachments:shm.diff (text/x-diff, 1.5K) downloaddiff --git a/src/backend/storage/ipc/shm_mq.c b/src/backend/storage/ipc/shm_mq.cnew file mode 100644index 3faace2..c80cb6e
*** a/src/backend/storage/ipc/shm_mq.c
--- b/src/backend/storage/ipc/shm_mq.c
*************** shm_mq_sendv(shm_mq_handle *mqh, shm_mq_
*** 493,499 ****
return SHM_MQ_DETACHED;
/*
! * If the counterpary is known to have attached, we can read mq_receiver
* without acquiring the spinlock and assume it isn't NULL. Otherwise,
* more caution is needed.
*/
--- 493,499 ----
return SHM_MQ_DETACHED;
/*
! * If the counterparty is known to have attached, we can read mq_receiver
* without acquiring the spinlock and assume it isn't NULL. Otherwise,
* more caution is needed.
*/
*************** shm_mq_inc_bytes_read(shm_mq *mq, Size n
*** 1203,1211 ****
/*
* Separate prior reads of mq_ring from the increment of mq_bytes_read
! * which follows. Pairs with the full barrier in shm_mq_send_bytes(). We
! * only need a read barrier here because the increment of mq_bytes_read is
! * actually a read followed by a dependent write.
*/
pg_read_barrier();
--- 1203,1211 ----
/*
* Separate prior reads of mq_ring from the increment of mq_bytes_read
! * which follows. This pairs with the full barrier in shm_mq_send_bytes().
! * We only need a read barrier here because the increment of mq_bytes_read
! * is actually a read followed by a dependent write.
*/
pg_read_barrier();
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To: pgsql-hackers@postgresql.org
Cc: bruce@momjian.us, nospam-pg-abuse@bloodgate.com, robertmhaas@gmail.com, andres@anarazel.de, amit.kapila16@gmail.com, rafia.sabih@enterprisedb.com
Subject: Re: [HACKERS] [POC] Faster processing at Gather node
In-Reply-To: <20180329161843.GC16165@momjian.us>
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