So it's definitely not related to Vary, there's no such header in requests I tried. Also this issue affects squid even with 1 worker if shared memory is forced to on.
Interesting thing I noticed is that according to log file a lot of images are actually cached in memory but sound files are not (mp3/wav). It's not like it makes any sense but how about random example url: http://techslides.com/demos/samples/sample.mp3 squid 4, 2 workers, shared cache, no disk cache – MEM_HIT squid 3, same config – MISS every time squid 3, no shared cache – MEM_HIT Could you do a brief test with this URL may be and confirm that I'm not the only one who see this issue? On Tue, Jan 16, 2018 at 6:25 AM, Alex Rousskov < rouss...@measurement-factory.com> wrote: > On 01/15/2018 09:25 PM, Ivan Larionov wrote: > > My total hit ratio decreased in ~2 times from 40% to 20% > > > On 01/14/2018 10:53 PM, Ivan Larionov wrote: > > > > > After migrating squid from non-SMP/aufs to SMP/rock memory cache > hit > > > ratio dropped significantly. Like from 50-100% to 1-5%. > > > > > And disk cache hit ratio went up from 15-50% to stable 60-65%. > > > The combination of the three statements above may be a sign of a problem > unrelated to Vary: Since the disk cache can cache everything the memory > cache can and is typically much larger than the memory cache, the > incapacitation of a memory cache (due to Vary) should not have a > significant effect on overall hit ratio. It should only affect hit > response time. > > The only known culprit I can think of in this context are hits for > being-cached objects: Rock lacks code that allows Squid to read > being-written objects. The shared memory cache has that code already. If > your workload has a lot of cases where clients request a being-written > object, then the overall hit ratio should go down after the memory cache > incapacitation (due to Vary). > > I suspect something else is in play here though, especially if you see a > different picture with Squid v4 -- the known problem discussed above is > present in all Squid versions. I second Amos's recommendation to focus > on v4 because it is unlikely that any complicated problems are going to > be fixed in v3, even if you triage them well. > > > HTH, > > Alex. > -- With best regards, Ivan Larionov.
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