27 Nov
2008
27 Nov
'08
4:15 p.m.
Hello,
There seem to be many places where static buffers are used for building
strings. It is clear they are used just for usage inside some functions,
with no need to keep the value for usage somewhere else.
Would defining a global static buffer to be used for such cases make
sense? The access to the pointer and size can be given via functions.
There could be couple of such buffers to be used in the cases one
function need concurrent access to more than one ... opinions? It will
reduce memory space reserved and used...
Cheers,
Daniel
--
Daniel-Constantin Mierla
http://www.asipto.com
27 Nov
27 Nov
4:22 p.m.
New subject: [SR-Dev] [Kamailio-Devel] static buffers
On Thursday 27 November 2008, Daniel-Constantin Mierla wrote:
There seem to be many places where static buffers are
used for building
strings. It is clear they are used just for usage inside some functions,
with no need to keep the value for usage somewhere else.
Would defining a global static buffer to be used for such cases make
sense? The access to the pointer and size can be given via functions.
There could be couple of such buffers to be used in the cases one
function need concurrent access to more than one ... opinions? It will
reduce memory space reserved and used...
Hi Daniel,
what about getting rid of this static buffers completely? If we want to go
multi-threaded sometimes, we need to lock every access. And i doubt it really
makes a difference from the performance POV nowadays. The only issue i could
think of is eventual memory fragementation..
Cheers,
Henning
4:51 p.m.
New subject: [SR-Dev] [Kamailio-Devel] static buffers
On Nov 27, 2008 at 16:22, Henning Westerholt <henning.westerholt(a)1und1.de> wrote:
On Thursday 27 November 2008, Daniel-Constantin Mierla
wrote:
We could use buffers on the stack as much as possible (we don't need to
pkg_malloc all the buffers).
Andrei
There seem to be many places where static buffers
are used for building
strings. It is clear they are used just for usage inside some functions,
with no need to keep the value for usage somewhere else.
Would defining a global static buffer to be used for such cases make
sense? The access to the pointer and size can be given via functions.
There could be couple of such buffers to be used in the cases one
function need concurrent access to more than one ... opinions? It will
reduce memory space reserved and used...
Hi Daniel,
what about getting rid of this static buffers completely? If we want to go
multi-threaded sometimes, we need to lock every access. And i doubt it really
makes a difference from the performance POV nowadays. The only issue i could
think of is eventual memory fragementation..
5:27 p.m.
New subject: [SR-Dev] [Kamailio-Devel] static buffers
On 11/27/08 17:51, Andrei Pelinescu-Onciul wrote:
yes, but is it advisable to do it with big buffers ... ?
Cheers,
Daniel
--
Daniel-Constantin Mierla
http://www.asipto.com
On Nov 27, 2008 at 16:22, Henning Westerholt
<henning.westerholt(a)1und1.de> wrote:
> On Thursday 27 November 2008, Daniel-Constantin Mierla wrote:
>
>> There seem to be many places where static buffers are used for building
>> strings. It is clear they are used just for usage inside some functions,
>> with no need to keep the value for usage somewhere else.
>>
>> Would defining a global static buffer to be used for such cases make
>> sense? The access to the pointer and size can be given via functions.
>>
>> There could be couple of such buffers to be used in the cases one
>> function need concurrent access to more than one ... opinions? It will
>> reduce memory space reserved and used...
>>
> Hi Daniel,
>
> what about getting rid of this static buffers completely? If we want to go
> multi-threaded sometimes,
he, he ... let's look closer in the future ... and from management
perspective looks easier if they are collected in one place.
we need to
lock every access. And i doubt it really
makes a difference from the performance POV nowadays. The only issue i could
think of is eventual memory fragementation..
We could use buffers on the stack as much as possible (we don't need to
pkg_malloc all the buffers).
5:59 p.m.
New subject: [SR-Dev] [Kamailio-Devel] static buffers
On Nov 27, 2008 at 18:27, Daniel-Constantin Mierla <miconda(a)gmail.com> wrote:
On 11/27/08 17:51, Andrei Pelinescu-Onciul wrote:
yes, but is it advisable to do it with big buffers ... ?
It depends, but in general yes, unless you have something very big.
A few k shouldn't be any problem,
The performance overhead is only 1 cycle when entering the function,
when using the stack (sp-=sizeof(buffer)) and from the cache point of
view there is no difference since you write to it anyway.
Andrei
On Nov 27, 2008 at 16:22, Henning Westerholt
<henning.westerholt(a)1und1.de> wrote:
>On Thursday 27 November 2008, Daniel-Constantin Mierla wrote:
>
>>There seem to be many places where static buffers are used for building
>>strings. It is clear they are used just for usage inside some functions,
>>with no need to keep the value for usage somewhere else.
>>
>>Would defining a global static buffer to be used for such cases make
>>sense? The access to the pointer and size can be given via functions.
>>
>>There could be couple of such buffers to be used in the cases one
>>function need concurrent access to more than one ... opinions? It will
>>reduce memory space reserved and used...
>>
>Hi Daniel,
>
>what about getting rid of this static buffers completely? If we want to
>go multi-threaded sometimes,
he, he ... let's look closer in the future ... and from management
perspective looks easier if they are collected in one place.
we need
to lock every access. And i doubt it really
makes a difference from the performance POV nowadays. The only issue i
could think of is eventual memory fragementation..
We could use buffers on the stack as much as possible (we don't need to
pkg_malloc all the buffers).
4:48 p.m.
New subject: [SR-Dev] static buffers
On Nov 27, 2008 at 17:15, Daniel-Constantin Mierla <miconda(a)gmail.com> wrote:
Hello,
There seem to be many places where static buffers are used for building
strings. It is clear they are used just for usage inside some functions,
with no need to keep the value for usage somewhere else.
Would defining a global static buffer to be used for such cases make
sense? The access to the pointer and size can be given via functions.
In general I think we should move away from static buffers
(we will need to get rid of a lot of them for the async. stuff so
most of this work will have to be redone anyway).
There could be couple of such buffers to be used in the cases one
function need concurrent access to more than one ... opinions? It will
reduce memory space reserved and used...
I'm afraid it would introduce a lot of new bugs (you must make sure your
functions that call each other do not use the same static buffer and
that you do not call function using the same buffer in a row).
As far as the memory space is concerned, it depends on how many of them
are used.
At least in sip-router core less then 1Mb is used in static vars of all
kinds:
objdump -j .bss -j .data -t ser|perl -ne 'END { print "\nTotal: $s
bytes\n" }; @l=split; $s+= hex $l[4]; print hex($l[4]),
"\t-\t$l[5]\t$l[1]\t$l[2]\t$l[3]\n" '
=> Total: 4604741 bytes in staitic vars, but 4M is the pkg mem pool
=> 410437 bytes from which 2*139276 are tcp local timers and
65k udp recv buffers => 66349 in other static vars and buffers.
So I guess it doesn't make sense to try to go beyond 66k...
Andrei
5:20 p.m.
New subject: [SR-Dev] static buffers
On 11/27/08 17:48, Andrei Pelinescu-Onciul wrote:
in the modules might be bigger... I think with 5 buffers, each of 1k, we
can satisfy all needs.
Cheers,
Daniel
On Nov 27, 2008 at 17:15, Daniel-Constantin Mierla
<miconda(a)gmail.com> wrote:
these are one time usage, without any concurrency. They are basically
used inside functions to avoid alloc/free for each function. I think
this is not affected by async stuff.
Hello,
There seem to be many places where static buffers are used for building
strings. It is clear they are used just for usage inside some functions,
with no need to keep the value for usage somewhere else.
Would defining a global static buffer to be used for such cases make
sense? The access to the pointer and size can be given via functions.
In general I think we should move away from static buffers
(we will need to get rid of a lot of them for the async. stuff so
most of this work will have to be redone anyway).
There could be couple of such buffers to be used
in the cases one
function need concurrent access to more than one ... opinions? It will
reduce memory space reserved and used...
I'm afraid it would introduce a lot of new bugs (you must make sure your
functions that call each other do not use the same static buffer and
that you do not call function using the same buffer in a row).
As far as the memory space is concerned, it depends on how many of them
are used.
At least in sip-router core less then 1Mb is used in static vars of all
kinds:
objdump -j .bss -j .data -t ser|perl -ne 'END {
print "\nTotal: $s
bytes\n" }; @l=split; $s+= hex $l[4]; print hex($l[4]),
"\t-\t$l[5]\t$l[1]\t$l[2]\t$l[3]\n" '
=> Total: 4604741 bytes in staitic vars, but 4M is the pkg mem pool
=> 410437 bytes from which 2*139276 are tcp local timers and
65k udp recv buffers => 66349 in other static vars and buffers.
So I guess it doesn't make sense to try to go beyond 66k...
Andrei
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--
Daniel-Constantin Mierla
http://www.asipto.com
5830
days inactive
5830
days old
6 comments
3 participants
participants (3)
-
Andrei Pelinescu-Onciul -
Daniel-Constantin Mierla -
Henning Westerholt