# Low Latency - Preemptive kernel?

## metalhedd

after i installed gentoo 1.1a i had to immediately upgrade to kernel 2.4.19pre10 to get my IDE controller to work, does this mean I missed the benefits of gentoo's Low latency Pre-emptive kernel? What exactly is this patch, what does it do? and is it possible for me to take advantage of it with the 2.4.19-pre10 kernel?

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## delta407

The low latency and preemtible kernel patches are two separate sets of changes. Low latency breaks up large kernel processes into several smaller ones, and the preemptive patch allows the kernel to interrupt itself to handle some other event (like an I/O completion, for instance). Both can be applied at once, and both can be applied to 2.4.19-pre10. You can read up on it at great length here.

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## c_kuzmanic

Running both patches (low latency and pre-emptive) gave me problems with stability. I only run pre-emptive now and that works just fine.Last edited by c_kuzmanic on Sun Jun 09, 2002 12:38 am; edited 1 time in total

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## tomte

 *c_kuzmanic wrote:*   

> Running both patches (low latency and pre-emptive) gave me problems with stabilty. I only run pre-emptive now and that works just fine.

 

I second this;

regards,

tom

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## arkane

 *tomte wrote:*   

>  *c_kuzmanic wrote:*   Running both patches (low latency and pre-emptive) gave me problems with stabilty. I only run pre-emptive now and that works just fine. 
> 
> I second this;
> 
> regards,
> ...

 

I've actually had mixed issues with both.  None were show stoppers, but was trivial slowdowns at the wrong times. (IMHO, YMMV)

I use my machine as a desktop machine and a server, so I guess I might be asking too much from the patches  :Smile:   I was using mozilla, openoffice, and emerge at the same time and mozilla would cludge along with the Pre-emptive patch in, where without it all of them would work like a charm.

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## FINITE

Isn't the preempt and low latency included in the gentoo kernel 2.4.19***?

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## delta407

I believe gentoo-sources uses both patches, plus a number of other things.

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## c_kuzmanic

 *delta407 wrote:*   

> I believe gentoo-sources uses both patches, plus a number of other things.

 

Yes it does. If you want to know specifics about what a kernel includes, just cat  the ebuild - it's all documented there.

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