Hi Amos, On Sat, 25 Apr 2009, Amos Jeffries wrote: >> ipcache_low 90 >> # ipcache_high 95 >> ipcache_high 95 >> cache_mem 1024 MB >> # cache_swap_low 90 >> cache_swap_low 90 >> # cache_swap_high 95 >> cache_swap_high 95 > > For cache >1GB the difference of 5% between high/low can mean long > periods spent garbage-collecting the disk storage. This is a major drag. > You can shrink the gap if you like less disk delay there. Could you elaborate on this a little? If I understand correctly from the comments in the template squid.conf: (swap_usage < cache_swap_low) -> no cache removal (cache_swap_low < swap_usage < cache_swap_high) -> cache removal attempts to maintain (swap_usage == cache_swap_log) (swap_usage ~> cache_swap_high) -> cache removal becomes aggressive until (swap_usage == cache_swap_log) It seems like you're saying that aggressive removal is a big drag on the disk so you should hit it early rather than late so the drag is not for a long period. Would it be better to calculate an absolute figure (say 200MB) and work out what percentage of your cache that is? It seems like the 95% high watermark is probably quite low for large caches too? I have 2x400GB caches. A 5% gap would leave 20GB to delete aggressively which might take quite some time alright. A 500MB gap would be 0.125. cache_swap_low 97.875 cache_swap_high 98 Can we use floating point numbers here? Would it make more sense for squid to offer absolute watermarks (in MB offset from the total size)? Gavin
