Problem changing from a One procesor machine to dual machine (sun solaris)

Problem changing from a One procesor machine to dual machine (sun solaris)

Post by Richard Poblet » Thu, 16 Dec 1999 04:00:00



we need to solve a problem with our applications, because when they were
running on a one processor machine they had an acceptable performance, but
now, running on a dual processor machine they are having a low performance
regarding to the previous machine.
 
 
 

Problem changing from a One procesor machine to dual machine (sun solaris)

Post by David Owe » Thu, 16 Dec 1999 04:00:00



> we need to solve a problem with our applications, because when they were
> running on a one processor machine they had an acceptable performance, but
> now, running on a dual processor machine they are having a low performance
> regarding to the previous machine.

If you read the P&T guide, simply adding processors does not always
guarantee a big performance boost.  It all depends on the applications
using the database.  A Sybase engineer was in here recently and did
some magic maths (that he was not prepared to disclose :-( ) and
recommended that we reduce the number of engines in order to get a
small performance boost.  Remember that with two engines, you now have
other things to bear in mind.  Each process now needs to acquire a
spinlock in order to access memory in order to ensure integrity.
There are other factors too.  What version of Sybase.  Some of the
older versions had an SMP "feature" whereby all of the newtork I/O was
performed by a single engine.  Even today, all of the network I/O for
a process goes through the engine that it initially connects to.

Give some more info (version of Sybase, number and type of
applications, size of memory, size of databases etc) and I am sure
that someone will be able to help.

dowen

 
 
 

Problem changing from a One procesor machine to dual machine (sun solaris)

Post by Richard Poblet » Thu, 16 Dec 1999 04:00:00


Server:
    SUN ULTRA ENTERPRISE 450 WITH 2 PROCESSORS.
    1 GB RAM
    There are four engines running on the server.
    The first one uses 400MB of shared memory.
    The others uses 100MB each one.

SYBASE
    SqlServer /11.0.3.3/P/Sun_srv4/OS5.4

Applications are Client-Server and uses essentially stored procedures.

DataBases:
The first engine has 21 databases, included system databases, with a total
size of 8GB.
The number of concurrent connections is 70.

David Owen escribi en mensaje ...


>> we need to solve a problem with our applications, because when they were
>> running on a one processor machine they had an acceptable performance,
but
>> now, running on a dual processor machine they are having a low
performance
>> regarding to the previous machine.

>If you read the P&T guide, simply adding processors does not always
>guarantee a big performance boost.  It all depends on the applications
>using the database.  A Sybase engineer was in here recently and did
>some magic maths (that he was not prepared to disclose :-( ) and
>recommended that we reduce the number of engines in order to get a
>small performance boost.  Remember that with two engines, you now have
>other things to bear in mind.  Each process now needs to acquire a
>spinlock in order to access memory in order to ensure integrity.
>There are other factors too.  What version of Sybase.  Some of the
>older versions had an SMP "feature" whereby all of the newtork I/O was
>performed by a single engine.  Even today, all of the network I/O for
>a process goes through the engine that it initially connects to.

>Give some more info (version of Sybase, number and type of
>applications, size of memory, size of databases etc) and I am sure
>that someone will be able to help.

>dowen

 
 
 

Problem changing from a One procesor machine to dual machine (sun solaris)

Post by Anthony Mandi » Fri, 17 Dec 1999 04:00:00



>     SUN ULTRA ENTERPRISE 450 WITH 2 PROCESSORS.
>     1 GB RAM
>     There are four engines running on the server.

        Er ... you only have 2 CPUs. You shouldn't have more
        than that many engines then.

Quote:>     The first one uses 400MB of shared memory.
>     The others uses 100MB each one.

        Er ... they should all be using the same shared memory.
        These engines are all within the same Sybase server
        aren't they?

Quote:> SYBASE
>     SqlServer /11.0.3.3/P/Sun_srv4/OS5.4
> DataBases:
> The first engine has 21 databases, included system databases, with a total
> size of 8GB.

        Your use of the word "engine" seems confusing. You statement
        here "the first engine" in particular. Do you mean you have
        more than one Sybase server instance? Or one instance
        configured with 4 engines? If the latter they should all
        see the same number of databases. One point to note, if your
        platform only runs Sybase, then you should have plenty of
        free memory. Try allocating more to Sybase after you confirm this.

-am

 
 
 

Problem changing from a One procesor machine to dual machine (sun solaris)

Post by Richard Poblet » Fri, 17 Dec 1999 04:00:00


Sorry, we have 4 Sybase server instances and the machine 2 CPUs.

we have made some tests with applications that were not programmed for 2
CPUs, and the sybase server instance configured with "min online engines=2"
, and when we compared the results, they were completelly diferent. Is it
because the sequence of the proccesses is not respected or considered by the
sybase server?

All of the sybase server instances are configured with the default values.
we only changed the following:
the number of open DB = 20
the number of users connections = 125
the number of devices = 15
shared memory = 400MB
and the number of locks = 15000

the rest of the parameters have the default values

thanks



>>     SUN ULTRA ENTERPRISE 450 WITH 2 PROCESSORS.
>>     1 GB RAM
>>     There are four engines running on the server.

> Er ... you only have 2 CPUs. You shouldn't have more
> than that many engines then.

>>     The first one uses 400MB of shared memory.
>>     The others uses 100MB each one.

> Er ... they should all be using the same shared memory.
> These engines are all within the same Sybase server
> aren't they?

>> SYBASE
>>     SqlServer /11.0.3.3/P/Sun_srv4/OS5.4

>> DataBases:
>> The first engine has 21 databases, included system databases, with a
total
>> size of 8GB.

> Your use of the word "engine" seems confusing. You statement
> here "the first engine" in particular. Do you mean you have
> more than one Sybase server instance? Or one instance
> configured with 4 engines? If the latter they should all
> see the same number of databases. One point to note, if your
> platform only runs Sybase, then you should have plenty of
> free memory. Try allocating more to Sybase after you confirm this.

>-am