Re: [HACKERS] Experimental dynamic memory allocation of postgresql shared memory

On Mon, Jun 20, 2016 at 12:40 PM, Craig Ringer wrote: > On 18 June 2016 at 02:42, Robert Haas wrote: >> >> On Fri, Jun 17, 2016 at 2:23 PM, Aleksey Demakov >> wrote: >> > Essentially this is pessimizing for the lowest common

Re: [HACKERS] Experimental dynamic memory allocation of postgresql shared memory

On 18 June 2016 at 02:42, Robert Haas wrote: > On Fri, Jun 17, 2016 at 2:23 PM, Aleksey Demakov > wrote: > > Essentially this is pessimizing for the lowest common denominator > > among OSes. > > I totally agree. That's how we make the server portable.

Re: [HACKERS] Experimental dynamic memory allocation of postgresql shared memory

On Sat, Jun 18, 2016 at 3:43 AM, Tom Lane wrote: > DSM already exists, and for many purposes its lack of a > within-a-shmem-segment dynamic allocator is irrelevant; the same purpose > is served (with more speed, more reliability, and less code) by releasing > the whole DSM

Re: [HACKERS] Experimental dynamic memory allocation of postgresql shared memory

Aleksey Demakov writes: > On Sat, Jun 18, 2016 at 12:45 AM, Tom Lane wrote: >> You're right, but that doesn't mean that the community is going to take >> much interest in an unportable replacement for code that already exists. > Excuse me, what code

Re: [HACKERS] Experimental dynamic memory allocation of postgresql shared memory

On Sat, Jun 18, 2016 at 12:45 AM, Tom Lane wrote: > Aleksey Demakov writes: >> On Fri, Jun 17, 2016 at 10:54 PM, Robert Haas wrote: >>> In my opinion, that's not going to fly. If I thought otherwise, I >>> would not have developed

Re: [HACKERS] Experimental dynamic memory allocation of postgresql shared memory

Aleksey Demakov writes: > On Fri, Jun 17, 2016 at 10:54 PM, Robert Haas wrote: >> On Fri, Jun 17, 2016 at 12:34 PM, Aleksey Demakov wrote: >>> I believe it would be perfectly okay to allocate huge amount of address >>> space with

Re: [HACKERS] Experimental dynamic memory allocation of postgresql shared memory

On Fri, Jun 17, 2016 at 2:23 PM, Aleksey Demakov wrote: > Essentially this is pessimizing for the lowest common denominator > among OSes. I totally agree. That's how we make the server portable. > Having a contiguous address space makes things so > much simpler that

Re: [HACKERS] Experimental dynamic memory allocation of postgresql shared memory

On Fri, Jun 17, 2016 at 2:23 PM, Aleksey Demakov wrote: > On Fri, Jun 17, 2016 at 10:54 PM, Robert Haas > wrote: > > On Fri, Jun 17, 2016 at 12:34 PM, Aleksey Demakov > wrote: > >>> I expect that to be useful for parallel query and

Re: [HACKERS] Experimental dynamic memory allocation of postgresql shared memory

On Sat, Jun 18, 2016 at 12:31 AM, Andres Freund wrote: > On 2016-06-18 00:23:14 +0600, Aleksey Demakov wrote: >> Finally, it's possible to repeatedly mmap >> and munmap on portions of a contiguous address space providing >> a given addr argument for both of them. The last

Re: [HACKERS] Experimental dynamic memory allocation of postgresql shared memory

Sorry for unclear language. Late Friday evening in my place is to blame. On Sat, Jun 18, 2016 at 12:23 AM, Aleksey Demakov wrote: > On Fri, Jun 17, 2016 at 10:54 PM, Robert Haas wrote: >> On Fri, Jun 17, 2016 at 12:34 PM, Aleksey Demakov

Re: [HACKERS] Experimental dynamic memory allocation of postgresql shared memory

On 2016-06-18 00:23:14 +0600, Aleksey Demakov wrote: > Finally, it's possible to repeatedly mmap > and munmap on portions of a contiguous address space providing > a given addr argument for both of them. The last option might, of > course, is susceptible to hijacking this portion of the address by

Re: [HACKERS] Experimental dynamic memory allocation of postgresql shared memory

On Fri, Jun 17, 2016 at 10:54 PM, Robert Haas wrote: > On Fri, Jun 17, 2016 at 12:34 PM, Aleksey Demakov wrote: >>> I expect that to be useful for parallel query and anything else where >>> processes need to share variable-size data. However, that's

Re: [HACKERS] Experimental dynamic memory allocation of postgresql shared memory

On Fri, Jun 17, 2016 at 12:34 PM, Aleksey Demakov wrote: >> I expect that to be useful for parallel query and anything else where >> processes need to share variable-size data. However, that's different >> from this because ours can grown to arbitrary size and shrink again by

Re: [HACKERS] Experimental dynamic memory allocation of postgresql shared memory

On Fri, Jun 17, 2016 at 10:18 PM, Robert Haas wrote: > On Fri, Jun 17, 2016 at 11:30 AM, Tom Lane wrote: > But I'm a bit confused about where it gets the bytes it wants to > manage. There's no call to dsm_create() or ShmemAlloc() anywhere in > the

Re: [HACKERS] Experimental dynamic memory allocation of postgresql shared memory

On Fri, Jun 17, 2016 at 9:30 PM, Tom Lane wrote: > Aleksey Demakov writes: >> I have some very experimental code to enable dynamic memory allocation >> of shared memory for postgresql backend processes. > > Um ... what's this do that the existing DSM stuff

Re: [HACKERS] Experimental dynamic memory allocation of postgresql shared memory

On Fri, Jun 17, 2016 at 11:30 AM, Tom Lane wrote: > Aleksey Demakov writes: >> I have some very experimental code to enable dynamic memory allocation >> of shared memory for postgresql backend processes. > > Um ... what's this do that the existing DSM

Re: [HACKERS] Experimental dynamic memory allocation of postgresql shared memory

Aleksey Demakov writes: > I have some very experimental code to enable dynamic memory allocation > of shared memory for postgresql backend processes. Um ... what's this do that the existing DSM stuff doesn't do? regards, tom lane -- Sent via

[HACKERS] Experimental dynamic memory allocation of postgresql shared memory

Hi all, I have some very experimental code to enable dynamic memory allocation of shared memory for postgresql backend processes. The source code in the repository is not complete yet. Moreover it is not immediately useful by itself. However it might serve as the basis to implement higher-level