[ELDK] Jumbo Frames, sil24 SATA driver, and kswapd0 page allocation failures

Wolfgang Denk wd at denx.de
Wed Aug 12 22:51:14 CEST 2009

Dear Jonathan Haws,

In message <BB99A6BA28709744BF22A68E6D7EB51F01FE471A5C at midas.usurf.usu.edu> you wrote:
> The reason I claim that the sil driver is not releasing memory is because when I run a program that simply writes data to our disk and monitor the amount of free memory available, it drops to almost nothing (just a couple of megabytes).  When I do a cat
>  /proc/buddyinfo, I get dangerously low on available pages.
> ~ # free
>               total         used         free       shared      buffers
>   Mem:       256672       249820         6852            0          208
>  Swap:            0            0            0
> Total:       256672       249820         6852

This looks perfectly OK. What exactly is your problem?

A low count of free pages? Well, be thankful for it that Linux puts
your expensive RAM to some use instead of leaving it unused.

> In my first email I said that things would work when I just ran the sil driver - what I really mean is, though I run low on memory, the kernel does not crash.  Only when I am capturing data on the network does it crash (if I am also writing that data to
>  disk).

Um... could you please mind the netiquette and use a shorter line
length - say some 70+ characters or so?  Thanks.

> What it seems like to me is that the write() system call is causing the driver to allocate some memory to setup the DMA to the disk.  Once that is complete, the memory does not seem to get released back to the kernel.  Things are getting released to an 

This is pure speculation, without any facts to base it on, right?

Best regards,

Wolfgang Denk

DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
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