From: | Dilip Kumar <dilipbalaut(at)gmail(dot)com> |
---|---|
To: | Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru> |
Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Merlin Moncure <mmoncure(at)gmail(dot)com>, Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, YUriy Zhuravlev <u(dot)zhuravlev(at)postgrespro(dot)ru>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Move PinBuffer and UnpinBuffer to atomics |
Date: | 2016-03-22 04:57:04 |
Message-ID: | CAFiTN-skAMbHyXGYt+moeFSN4iOW5r+D30Hgetfn5C3262WP0g@mail.gmail.com |
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Lists: | pgsql-hackers |
On Tue, Mar 22, 2016 at 12:31 PM, Dilip Kumar <dilipbalaut(at)gmail(dot)com> wrote:
> ! pg_atomic_write_u32(&bufHdr->state, state);
> } while (!StartBufferIO(bufHdr, true));
>
> Better Write some comment, about we clearing the BM_LOCKED from stage
> directly and need not to call UnlockBufHdr explicitly.
> otherwise its confusing.
>
Few more comments..
*** 828,837 ****
*/
do
{
! LockBufHdr(bufHdr);
*! Assert(bufHdr->flags & BM_VALID);*
! bufHdr->flags &= ~BM_VALID;
! UnlockBufHdr(bufHdr);
} while (!StartBufferIO(bufHdr, true));
}
}
--- 826,834 ----
*/
do
{
! uint32 state = LockBufHdr(bufHdr);
! state &= ~(BM_VALID | BM_LOCKED);
! pg_atomic_write_u32(&bufHdr->state, state);
} while (!StartBufferIO(bufHdr, true));
1. Previously there was a Assert, any reason why we removed it ?
Assert(bufHdr->flags & BM_VALID);
2. And also if we don't need assert then can't we directly clear BM_VALID
flag from state variable (if not locked) like pin/unpin buffer does,
without taking buffer header lock?
--
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com
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