Some more info: Following are mgr:storedir stats after back to back downloads for 4 GB data (ie same 2 GB twice). Perhaps the 477 StoreEntries with MemObjects AND 468 Hot Object Cache Items are not shared? <stats> Connection information for squid: Number of clients accessing cache: 10 Number of HTTP requests received: 78410 Number of ICP messages received: 0 Number of ICP messages sent: 0 Number of queued ICP replies: 0 Number of HTCP messages received: 0 Number of HTCP messages sent: 0 Request failure ratio: 0.00 Average HTTP requests per minute since start: 8167.3 Average ICP messages per minute since start: 0.0 Select loop called: 1228150 times, 4.226 ms avg Cache information for squid: Hits as % of all requests: 5min: 44.7%, 60min: 44.7% Hits as % of bytes sent: 5min: 44.9%, 60min: 44.9% Memory hits as % of hit requests: 5min: 0.0%, 60min: 0.0% Disk hits as % of hit requests: 5min: 88.9%, 60min: 88.9% Storage Swap size: 2454128 KB Storage Swap capacity: 1.2% used, 98.8% free Storage Mem size: 1980 KB Storage Mem capacity: 0.0% used, 0.0% free Mean Object Size: 62.81 KB Requests given to unlinkd: 0 Median Service Times (seconds) 5 min 60 min: HTTP Requests (All): 0.03394 0.03394 Cache Misses: 0.04430 0.04430 Cache Hits: 0.02041 0.02041 Near Hits: 0.00000 0.00000 Not-Modified Replies: 0.00000 0.00000 DNS Lookups: 0.02896 0.02896 ICP Queries: 0.00000 0.00000 Resource usage for squid: UP Time: 576.032 seconds CPU Time: 476.166 seconds CPU Usage: 82.66% CPU Usage, 5 minute avg: 118.39% CPU Usage, 60 minute avg: 88.17% Process Data Segment Size via sbrk(): 81444 KB Maximum Resident Size: 4967328 KB Page faults with physical i/o: 2 Memory usage for squid via mallinfo(): Total space in arena: 82632 KB Ordinary blocks: 75092 KB 4345 blks Small blocks: 0 KB 0 blks Holding blocks: 350592 KB 73 blks Free Small blocks: 0 KB Free Ordinary blocks: 7540 KB Total in use: 7540 KB 2% Total free: 7540 KB 2% Total size: 433224 KB Memory accounted for: Total accounted: 27358 KB 6% memPool accounted: 27358 KB 6% memPool unaccounted: 405866 KB 94% memPoolAlloc calls: 17695559 memPoolFree calls: 17764839 File descriptor usage for squid: Maximum number of file descriptors: 589824 Largest file desc currently in use: 35 Number of file desc currently in use: 135 Files queued for open: 0 Available number of file descriptors: 589689 Reserved number of file descriptors: 900 Store Disk files open: 1 Internal Data Structures: 477 StoreEntries 477 StoreEntries with MemObjects 468 Hot Object Cache Items 39070 on-disk objects </stats> On Tue, Feb 18, 2014 at 1:52 AM, Rajiv Desai <rajiv@xxxxxxxxxxxxxx> wrote: > Hello, > > Need some guidance for optimal sharing of cache amongst SMP workers > using Large rock. > > Context: > > I am using squid cache with 8 SMP workers and a 200 GB rock cache stored on SMP. > (Using squid-3.HEAD-20140127-r13248 which has LargeRock support to > cache objects > 32 KB). > > I have set : > maximum_object_size 4 MB > cache_dir rock /mnt/squid-cache 204800 max-size=4194304 > cache_mem 0 MB > > My refresh pattern is very permissive which basically allows caching everything: > refresh_pattern . 129600 100% 129600 ignore-auth > > > Questions: > > I am trying to test optimal caching behavior where after I have > downloaded 1 GB data (~16000 objects ~64KB each) the subsequent > download should all be cache hits. > However, I see several TCP misses in access.log. The hit ratio on > subsequent download of the same objects is ~85%. > > 1. Is this expected in a multiple worker setup? If yes, can you please > briefly explain what contributes towards these misses and how can this > be minimized? > > 2. I set cache_mem to 0 coz I believe cache_mem sharing is > opportunistic and hence all workers might not always share all objects > in cache_mem. Is that correct? What impact does cache_mem size have on > deterministic sharing of cache between workers. > > 3. Moreover are there any tips/guidelines to optimize % hit rate for > previously downloaded objects. > > Thanks, > Rajiv
