Re: quickie on 2.0 ramdisk and buffers (solved)

Bjorn Wesen (bjorn@sparta.lu.se)
Wed, 1 Dec 1999 17:24:42 +0100 (MET)

I dug deeper and found that the culprit was ext2 in combination with the
ramdisk. ext2 does bforget() instead of brelse() in ext2/truncate.c and
bforget effectively nukes the buffer out of the ramdisk, so a new one has
to be allocated next time the block is needed. It only happened when
something needed truncation.

(I had a problem with that because of some customized buffer cache
handling - I could just put the brelse instead and problem solved)

-Bjorn

On Wed, 1 Dec 1999, Bjorn Wesen wrote:

> I thought the idea with the ramdisk was that it is simply buffers that
> don't belong to a physical device. When creating, say, a 512 kbyte
> filesystem on /dev/ram0 the amount of buffers go up by about 512 kbyte so
> that's ok. And if I write a file to the mounted ramdisk the amount of
> buffers dont go up. But for example mkdir/rmdir causes yet more buffers to
> be allocated. I found that weird. Before I go digging deep, I just wanted
> to confirm that no more buffers should be allocated by the kernel for
> operations on the ramdisk blocks ? Filesystem was ext2, kernel 2.0.33.

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