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Old 08 November 2014, 13:09   #68
alewis
Monochrome and 8 bit

 
Join Date: Nov 2004
Location: Underbarrow, Gods Country
Age: 51
Posts: 580
Just a thought. The standard File systems used a block size of 512bytes, the standard buffer size was 512bytes. So adding 30 buffers per drive used 15Kb per drive/partition for each entry. Iirc it defaulted to 30 buffers per HD and 5 per floppy unless overridden in the RDB or startup-sequence.

SFS and PFS used a larger block size, partially to improve read performance and to cope with larger hard disks. As such, the size of a single buffer would need to increase to match the corresponding block size. Consequently, if a block was now 1024bytes, each buffer would be 1024bytes, and 30buffers would use 30kb. Did PFS not also include a disk cache? This would also use a buffer size that matches the block size, but would also be increased by the number of cache lines. Ie, a cache of 30 buffers with a line size of 10 would use 300Kb, as it is equivalent to 10 lots of 30 1024byte buffers.

I also have a vague memory that if you had buffers specified in RDB, having an addbuffers command in startup allocated those as additional buffers.

Probably wrong, as it's been nigh on 20years since I used a real Amiga in anger.
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