Because the interactivity of the system is better with less memory.
> Writing is delayed because that accumulate bigger writes and
> fewer seeks. This helps performance a lot. Delaying writes
> has another advantage - somw writes won't be done at all,
> saving 100% writing time. This is the case for temporary
> files that gets written to, read, and deleted before they
> get written to disk. It all happens in cache, improving
> performance tremendously. To see the alternative,
> try booting with mem=4M or 16M or some such, with _no_ swapping.
I see that. However, I don't see why the kernel is writing out data
as agressively as it does now. Delaying a write for 30 seconds isn't the
problem: the aggressive writes are. Since the disks are otherwise idle, the
kernel can gently start writing out the dirty cache. No need to try and
write 40 MB in 1 sec when you can write 10 MB/sec in 4 seconds.
[...]
> For more detailed information, read a book about how filesystems and
> disk caching works.
I'm just reporting what's happening to me in practice, I don't really care
about what should happen in theory.
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