virtual share memory too big ?
The poster (Informix 7.31 on HP-UX 11i, ~1000 sessions/1200 threads) saw multiple virtual shared-memory segments appear via 'onstat -g seg' and asked whether doubling SHMVIRTSIZE (640MB to 1280MB) could cause problems, including extra CPU use. Art Kagel answered that it's fine as long as the machine doesn't start swapping, and that unused memory isn't touched so there's no CPU penalty; he suggested also enlarging the buffer cache. theBP added tuning advice: RESIDENT -1 with plenty of RAM, check read/write cache rates and bufwaits, tune BUFFERS and LRUs, and size SHMVIRTSIZE so no SHMADD segments are needed. The poster thanked both; no further follow-up.
Auto-generated by DrWatson from the posts below — may be imperfect; read the full thread.
Environment: Informix 7.31
S.O. HP-UX 11i
I have an instance with an average workload of 1000 user sessions and
1200 threads. This instance have only one database with 2000 tables
approximately.
I have set the onconfig parameter SHMVIRTSIZE at 640 MB and SHMADD at
100 MB
Due to I see several virtual segments in onstat -g seg, I decided to
increase the SHMVIRTSIZE value
I have relatively a lot of memory in my server.
My question is:
Is there any issue if I increase SHMVIRTSIZE to a value so much
higher, for example the double (1280 MB) ?
What adverse effect could occur ?
No problem as long as it doesn't cause the system to begin to swap.
Art
Art S. Kagel
Oninit (www.oninit.com)
IIUG Board of Directors (art@iiug.org)
Disclaimer: Please keep in mind that my own opinions are my own opinions and
do not reflect on my employer, Oninit, the IIUG, nor any other organization
with which I am associated either explicitly or implicitly. Neither do
those opinions reflect those of other individuals affiliated with any entity
with which I am affiliated nor those of the entities themselves.
On Wed, Jun 3, 2009 at 5:38 PM, Peternt <roger_vilca@yahoo.es> wrote:
> Environment: Informix 7.31
> S.O. HP-UX 11i
>
>
> I have an instance with an average workload of 1000 user sessions and
> 1200 threads. This instance have only one database with 2000 tables
> approximately.
> I have set the onconfig parameter SHMVIRTSIZE at 640 MB and SHMADD at
> 100 MB
> Due to I see several virtual segments in onstat -g seg, I decided to
> increase the SHMVIRTSIZE value
>
> I have relatively a lot of memory in my server.
> My question is:
> Is there any issue if I increase SHMVIRTSIZE to a value so much
> higher, for example the double (1280 MB) ?
> What adverse effect could occur ?
> _______________________________________________
> Informix-list mailing list
> Informix-list@iiug.org
> http://www.iiug.org/mailman/listinfo/informix-list
>
On 3 jun, 16:55, Art Kagel <art.ka...@gmail.com> wrote:
> No problem as long as it doesn't cause the system to begin to swap.
>
> Art
>
> Art S. Kagel
> Oninit (www.oninit.com)
> IIUG Board of Directors (a...@iiug.org)
>
> Disclaimer: Please keep in mind that my own opinions are my own opinions and
> do not reflect on my employer, Oninit, the IIUG, nor any other organization
> with which I am associated either explicitly or implicitly. Neither do
> those opinions reflect those of other individuals affiliated with any entity
> with which I am affiliated nor those of the entities themselves.
>
> On Wed, Jun 3, 2009 at 5:38 PM, Peternt <roger_vi...@yahoo.es> wrote:
> > Environment: Informix 7.31
> > S.O. HP-UX 11i
>
> > I have an instance with an average workload of 1000 user sessions and
> > 1200 threads. This instance have only one database with 2000 tables
> > approximately.
> > I have set the onconfig parameter SHMVIRTSIZE at 640 MB and SHMADD at
> > 100 MB
> > Due to I see several virtual segments in onstat -g seg, I decided to
> > increase the SHMVIRTSIZE value
>
> > I have relatively a lot of memory in my server.
> > My question is:
> > Is there any issue if I increase SHMVIRTSIZE to a value so much
> > higher, for example the double (1280 MB) ?
> > What adverse effect could occur ?
> > _______________________________________________
> > Informix-list mailing list
> > Informix-l...@iiug.org
> >http://www.iiug.org/mailman/listinfo/informix-list
No problem with CPU utilization ?
No. IDS will only actually access the memory that it needs to resolve
queries, so, more memory doesn't mean more CPU cycles. If you have lots of
memory, look to maximize the buffer cache as well. You should be able to
keep at lease an hour's worth of working set data in memory. If you can get
that up to half a day or a full day's data, more power to you and your
server will cruise.
Art
Art S. Kagel
Oninit (www.oninit.com)
IIUG Board of Directors (art@iiug.org)
Disclaimer: Please keep in mind that my own opinions are my own opinions and
do not reflect on my employer, Oninit, the IIUG, nor any other organization
with which I am associated either explicitly or implicitly. Neither do
those opinions reflect those of other individuals affiliated with any entity
with which I am affiliated nor those of the entities themselves.
On Wed, Jun 3, 2009 at 6:33 PM, Peternt <roger_vilca@yahoo.es> wrote:
> On 3 jun, 16:55, Art Kagel <art.ka...@gmail.com> wrote:
> > No problem as long as it doesn't cause the system to begin to swap.
> >
> > Art
> >
> > Art S. Kagel
> > Oninit (www.oninit.com)
> > IIUG Board of Directors (a...@iiug.org)
> >
> > Disclaimer: Please keep in mind that my own opinions are my own opinions
> and
> > do not reflect on my employer, Oninit, the IIUG, nor any other
> organization
> > with which I am associated either explicitly or implicitly. Neither do
> > those opinions reflect those of other individuals affiliated with any
> entity
> > with which I am affiliated nor those of the entities themselves.
> >
> > On Wed, Jun 3, 2009 at 5:38 PM, Peternt <roger_vi...@yahoo.es> wrote:
> > > Environment: Informix 7.31
> > > S.O. HP-UX 11i
> >
> > > I have an instance with an average workload of 1000 user sessions and
> > > 1200 threads. This instance have only one database with 2000 tables
> > > approximately.
> > > I have set the onconfig parameter SHMVIRTSIZE at 640 MB and SHMADD at
> > > 100 MB
> > > Due to I see several virtual segments in onstat -g seg, I decided to
> > > increase the SHMVIRTSIZE value
> >
> > > I have relatively a lot of memory in my server.
> > > My question is:
> > > Is there any issue if I increase SHMVIRTSIZE to a value so much
> > > higher, for example the double (1280 MB) ?
> > > What adverse effect could occur ?
> > > _______________________________________________
> > > Informix-list mailing list
> > > Informix-l...@iiug.org
> > >http://www.iiug.org/mailman/listinfo/informix-list
>
> No problem with CPU utilization ?
> _______________________________________________
> Informix-list mailing list
> Informix-list@iiug.org
> http://www.iiug.org/mailman/listinfo/informix-list
>
Art Kagel wrote:
> No. IDS will only actually access the memory that it needs to resolve
> queries, so, more memory doesn't mean more CPU cycles. If you have lots
> of memory, look to maximize the buffer cache as well. You should be
> able to keep at lease an hour's worth of working set data in memory. If
> you can get that up to half a day or a full day's data, more power to
> you and your server will cruise.
>
> Art
>
> Art S. Kagel
> Oninit (www.oninit.com <http://www.oninit.com>)
> IIUG Board of Directors (art@iiug.org <mailto:art@iiug.org>)
>
> Disclaimer: Please keep in mind that my own opinions are my own opinions
> and do not reflect on my employer, Oninit, the IIUG, nor any other
> organization with which I am associated either explicitly or implicitly.
> Neither do those opinions reflect those of other individuals affiliated
> with any entity with which I am affiliated nor those of the entities
> themselves.
>
>
>
> On Wed, Jun 3, 2009 at 6:33 PM, Peternt <roger_vilca@yahoo.es
> <mailto:roger_vilca@yahoo.es>> wrote:
>
> On 3 jun, 16:55, Art Kagel <art.ka...@gmail.com
> <mailto:art.ka...@gmail.com>> wrote:
> > No problem as long as it doesn't cause the system to begin to swap.
> >
> > Art
> >
> > Art S. Kagel
> > Oninit (www.oninit.com <http://www.oninit.com>)
> > IIUG Board of Directors (a...@iiug.org <mailto:a...@iiug.org>)
> >
> > Disclaimer: Please keep in mind that my own opinions are my own
> opinions and
> > do not reflect on my employer, Oninit, the IIUG, nor any other
> organization
> > with which I am associated either explicitly or implicitly.
> Neither do
> > those opinions reflect those of other individuals affiliated with
> any entity
> > with which I am affiliated nor those of the entities themselves.
> >
> > On Wed, Jun 3, 2009 at 5:38 PM, Peternt <roger_vi...@yahoo.es
> <mailto:roger_vi...@yahoo.es>> wrote:
> > > Environment: Informix 7.31
> > > S.O. HP-UX 11i
> >
> > > I have an instance with an average workload of 1000 user
> sessions and
> > > 1200 threads. This instance have only one database with 2000 tables
> > > approximately.
> > > I have set the onconfig parameter SHMVIRTSIZE at 640 MB and
> SHMADD at> > > 100 MB
> > > Due to I see several virtual segments in onstat -g seg, I
> decided to
> > > increase the SHMVIRTSIZE value
> >
> > > I have relatively a lot of memory in my server.
> > > My question is:
> > > Is there any issue if I increase SHMVIRTSIZE to a value so much
> > > higher, for example the double (1280 MB) ?
> > > What adverse effect could occur ?
> > > _______________________________________________
> > > Informix-list mailing list
> > > Informix-l...@iiug.org <mailto:Informix-l...@iiug.org>
> > >http://www.iiug.org/mailman/listinfo/informix-list
>
> No problem with CPU utilization ?
> _______________________________________________
> Informix-list mailing list
> Informix-list@iiug.org <mailto:Informix-list@iiug.org>
> http://www.iiug.org/mailman/listinfo/informix-list
>
>
Is this 64bit?
How much RAM have you got?
Several things to consider ...
RESIDENT -1 (IF you have loads of RAM)
BUFFERS check your %read and %write cache rates and bufwaits and tried and get high read / write and low bufwaits - between 2 and 10
Mb per user depending on activity and increase LRUs to get about 5 Mb per LRU is a good start.
SHMVIRSTIZE ... try and set it so that you do not need to allocate more SHMADDs
etc. etc.
On 4 jun, 01:08, theBP <th...@Usenet-News.Net> wrote:
> Art Kagel wrote:
> > No. IDS will only actually access the memory that it needs to resolve
> > queries, so, more memory doesn't mean more CPU cycles. If you have lots
> > of memory, look to maximize the buffer cache as well. You should be
> > able to keep at lease an hour's worth of working set data in memory. If
> > you can get that up to half a day or a full day's data, more power to
> > you and your server will cruise.
>
> > Art
>
> > Art S. Kagel
> > Oninit (www.oninit.com<http://www.oninit.com>)
> > IIUG Board of Directors (a...@iiug.org <mailto:a...@iiug.org>)
>
> > Disclaimer: Please keep in mind that my own opinions are my own opinions
> > and do not reflect on my employer, Oninit, the IIUG, nor any other
> > organization with which I am associated either explicitly or implicitly.
> > Neither do those opinions reflect those of other individuals affiliated
> > with any entity with which I am affiliated nor those of the entities
> > themselves.
>
> > On Wed, Jun 3, 2009 at 6:33 PM, Peternt <roger_vi...@yahoo.es
> > <mailto:roger_vi...@yahoo.es>> wrote:
>
> > On 3 jun, 16:55, Art Kagel <art.ka...@gmail.com
> > <mailto:art.ka...@gmail.com>> wrote:
> > > No problem as long as it doesn't cause the system to begin to swap.
>
> > > Art
>
> > > Art S. Kagel
> > > Oninit (www.oninit.com<http://www.oninit.com>)
> > > IIUG Board of Directors (a...@iiug.org <mailto:a...@iiug.org>)
>
> > > Disclaimer: Please keep in mind that my own opinions are my own
> > opinions and
> > > do not reflect on my employer, Oninit, the IIUG, nor any other
> > organization
> > > with which I am associated either explicitly or implicitly.
> > Neither do
> > > those opinions reflect those of other individuals affiliated with
> > any entity
> > > with which I am affiliated nor those of the entities themselves.
>
> > > On Wed, Jun 3, 2009 at 5:38 PM, Peternt <roger_vi...@yahoo.es
> > <mailto:roger_vi...@yahoo.es>> wrote:
> > > > Environment: Informix 7.31
> > > > S.O. HP-UX 11i
>
> > > > I have an instance with an average workload of 1000 user
> > sessions and
> > > > 1200 threads. This instance have only one database with 2000 tables
> > > > approximately.
> > > > I have set the onconfig parameter SHMVIRTSIZE at 640 MB and
> > SHMADD at
> > > > 100 MB> > > > Due to I see several virtual segments in onstat -g seg, I
> > decided to
> > > > increase the SHMVIRTSIZE value
>
> > > > I have relatively a lot of memory in my server.
> > > > My question is:
> > > > Is there any issue if I increase SHMVIRTSIZE to a value so much
> > > > higher, for example the double (1280 MB) ?
> > > > What adverse effect could occur ?
> > > > _______________________________________________
> > > > Informix-list mailing list
> > > > Informix-l...@iiug.org <mailto:Informix-l...@iiug.org>
> > > >http://www.iiug.org/mailman/listinfo/informix-list
>
> > No problem with CPU utilization ?
> > _______________________________________________
> > Informix-list mailing list
> > Informix-l...@iiug.org <mailto:Informix-l...@iiug.org>
> > http://www.iiug.org/mailman/listinfo/informix-list
>
> Is this 64bit?
>
> How much RAM have you got?
>
> Several things to consider ...
>
> RESIDENT -1 (IF you have loads of RAM)
> BUFFERS check your %read and %write cache rates and bufwaits and tried and get high read / write and low bufwaits - between 2 and 10
> Mb per user depending on activity and increase LRUs to get about 5 Mb per LRU is a good start.
> SHMVIRSTIZE ... try and set it so that you do not need to allocate more SHMADDs
>
> etc. etc.
Thank you Art
Thank you theBP
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