Re: 2.4.5-ac1 won't boot with 4GB bigmem option

[Fabio Riccardi]

Same here, I have a dual 1GHz PIII with 4G, I don't get an oops but an infinite
loop of:

 > mm: critical shortage of bounce buffers.

Indeed this message has been pestering me in all the recent .4-acx kernels when
the machine is under heavy FS pressure.

In these kernels I observe a significative (5-10%) performance degradation as
soon as the FS cache fills up all the available memory, at this moment "kswapd"
starts to take lots of CPU time (10-20%) and I keep getting plenty of the above
messages.

I'm running SpecWeb with the X15 webserver, which uses sendfile to send its
content, and a very large file set (8-9G, more than twice as much as the
physical RAM).

2.4.2-acx and early 2.4.3-acx kernles were much better in this respect and a lot
more stable.

 - Fabio

Ben Twijnstra wrote:

> Hi,
>
> I compiled and booted the 2.4.5-ac1 kernel with the CONFIG_HIGHMEM4G=y option
> and got an oops in __alloc_pages() (called by alloc_bounce() called by
> schedule()). Everything works fine if I turn the 4GB mode off.
>
> Machine is a Dell Precision with 2 Xeons and 2GB of RAM.
>
> 2.4.5 works fine with the 4GB. Any idea what changed between the two?
>
> Grtz,
>
> Ben
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