Sorry, I don’t know why I didn’t spot that! Having increased the cache capacity, the measured hit rate now exactly matches the expected hit rate.
From: Leif Hedstrom [mailto:[email protected]] Sent: 14 July 2010 17:12 To: [email protected] Cc: Rob Maidment Subject: Re: why does cache hit rate tail off? On 07/14/2010 10:02 AM, Rob Maidment wrote: The old (LRU) algorithm made little difference. I guess it could be that I’m simply exceeding the cache capacity. The test uses a working set of 2.24GB. How do I configure the size of the cache? Two settings: In etc/trafficserver/storage.config, you will see a line similar to var/trafficserver 140M You'll want that closer to 2.24G I imagine :). For the RAM cache, the setting is in etc/trafficserver/records.config: CONFIG proxy.config.cache.ram_cache.size INT -1 The default (-1) means it'll calculate the RAM cache size based on the disk cache size; For every 1GB of disk cache, it uses 1MB of RAM cache (which is really small honestly). I'd definitely bump this up as much as your box can handle, but make sure to leave room for the connections and other buffers (setting this is a "trial and error", and is very application specific). Fwiw, an inactive connection consumes about 32KB of memory, and an active one doubles that (for additional buffers). SSL connections consumes even more memory. (I think this is an area where we might be able to improve too, patches are welcomed). I hope any of this helps your benchmarks (really looking forward to see your results). -- leif ________________________________ Message Processed by the MIMEsweeperTM SMTP Appliance This e-mail and any files transmitted with it are strictly confidential, may be privileged and are intended only for use by the addressee unless otherwise indicated. If you are not the intended recipient any use, dissemination, printing or copying is strictly prohibited and may be unlawful. If you have received this e-mail in error, please delete it immediately and contact the sender as soon as possible. Clearswift cannot be held liable for delays in receipt of an email or any errors in its content. Clearswift accepts no responsibility once an e-mail and any attachments leave us. Unless expressly stated, opinions in this message are those of the individual sender and not of Clearswift. This email message has been inspected by Clearswift for inappropriate content and security threats. To find out more about Clearswift’s solutions please visit www.clearswift.com
