Wolfgang Denk wrote:
In message <47AA08E7.5000801@xxxxxxx> you wrote:
I actually think the kernel should operate with block sizes
like this and not wth 4 kiB blocks. It is the readahead and the elevator
algorithms that save us from randomly reading 4 kb a time.
Exactly, and nothing save a R-A-RW cycle if the write is a partial chunk.
Indeed kernel page size is an important factor in such optimizations.
But you have to keep in mind that this is mostly efficient for (very)
large strictly sequential I/O operations only - actual file system
traffic may be *very* different.
That was actually what I meant by page size, that of the file system
rather than the memory, ie. the "block size" typically used for writes.
Or multiples thereof, obviously.
We implemented the option to select kernel page sizes of 4, 16, 64
and 256 kB for some PowerPC systems (440SPe, to be precise). A nice
graphics of the effect can be found here:
https://www.amcc.com/MyAMCC/retrieveDocument/PowerPC/440SPe/RAIDinLinux_PB_0529a.pdf
I started that online and pulled a download to print, very neat stuff.
Thanks for the link.
Best regards,
Wolfgang Denk
--
Bill Davidsen <davidsen@xxxxxxx>
"Woe unto the statesman who makes war without a reason that will still
be valid when the war is over..." Otto von Bismark
-
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
