Thank you for the analysis.
On 2015-01-09 10:46, Gilles Dubuc wrote:
The vast majority of Varnish misses merely pulls from Swift a thumbnail that has already been rendered at some earlier point in time and just happens to not have been requested for a while. And that Swift pull + Varnish re-add is what's making the majority of Varnish misses perform worse than hits, not the need to generate the thumbnail with ImageMagick.
It seems like the only way to increase image serving performance in our current setup is to increase the expiry value in Varnish and/or increase Varnish capacity. Right now 17% of image requests in Media Viewer are Varnish misses, and 99.5% of those are pulling an existing thumbnail from Swift. Varnish misses are twice as slow as hits on average.
Is the 2x time on the client from last request byte to first response byte or to last byte of response or even something else?
How could the setup be improved? Would directly hitting Swift from the client be better?