Question about varnishstat and hitrate

[Stig Bakken]

Varnish's cache hit rate is a percentage of hits among requests that went
through vcl_lookup, not all requests.

 - Stig

On Wed, Nov 2, 2011 at 10:53 AM, Connor Walls
<connor.walls at skillpages.com>wrote:

> Hi,****
>
> ** **
>
> I had a question about the numbers generated in varnishstat. Looking at
> the current hitrate average for one of our boxes is giving an average of
> 0.4833 for the last 1000 requests, and the hitrate is in and around this
> number on all of our varnish boxes. We are also recording the output of
> varnishlog to a file, including a “X-Cache” header, as per this article:
> https://www.varnish-cache.org/trac/wiki/VCLExampleHitMissHeader. Now,
> what I’m curious about is whenever I look at the responses that have been
> logged, <5% of them are being served from the cache, which is at odds with
> the 48% that varnishstat is reporting. Is the hitrate average only taking
> into account pages that are passed, and not pages that are fetched? Why is
> there such a discrepancy between the two values?****
>
> ** **
>
> Here’s a sample output from varnishstat, if it helps explain things better.
> ****
>
> ** **
>
> 4+18:04:37                                           domU-12-31-39-10-74-A8
> ****
>
> Hitrate ratio:       10      100     1000****
>
> Hitrate avg:     0.3646   0.4249   0.4833****
>
> ** **
>
>      1528600         3.96         3.72 Client connections accepted****
>
>     10346326        23.77        25.19 Client requests received****
>
>      5244804         0.99        12.77 Cache hits****
>
>         9509         0.00         0.02 Cache hits for pass****
>
>       147772         0.00         0.36 Cache misses****
>
>        22490         0.00         0.05 Backend conn. success****
>
>      4731723        21.79        11.52 Backend conn. reuses****
>
>        12459         0.00         0.03 Backend conn. was closed****
>
>      4744236        19.81        11.55 Backend conn. recycles****
>
>         9505         0.00         0.02 Fetch head****
>
>      4727908        20.80        11.51 Fetch with Length****
>
>         1751         0.00         0.00 Fetch chunked****
>
>          422          .            .   N struct sess_mem****
>
>           96          .            .   N struct sess****
>
>         4104          .            .   N struct object****
>
>         4148          .            .   N struct objectcore****
>
>         4115          .            .   N struct objecthead****
>
>           48          .            .   N struct vbe_conn****
>
>           53          .            .   N worker threads****
>
>         7788         0.00         0.02 N worker threads created****
>
>            0         0.00         0.00 N queued work requests****
>
>        32999         0.00         0.08 N overflowed work requests****
>
>            1          .            .   N backends****
>
>       136098          .            .   N expired objects****
>
>       397731          .            .   N LRU moved objects****
>
>      8861590        17.82        21.58 Objects sent with write****
>
>      1528600         3.96         3.72 Total Sessions****
>
>     10346326        23.77        25.19 Total Requests****
>
>      4600511        20.80        11.20 Total pass****
>
>      4744331        20.80        11.55 Total fetch****
>
>   5613543692     14549.86     13669.00 Total header bytes****
>
> 50230527274     64650.96    122311.52 Total body bytes****
>
>       398864         1.98         0.97 Session Closed****
>
>            1         0.00         0.00 Session Pipeline****
>
>      9989106        21.79        24.32 Session Linger****
>
>      4717398        17.82        11.49 Session herd****
>
>    731094771      2065.68      1780.22 SHM records****
>
>     29558086        95.06        71.97 SHM writes****
>
>        14131         0.00         0.03 SHM MTX contention****
>
>          353         0.00         0.00 SHM cycles through buffer****
>
>      3518804        16.83         8.57 SMA allocator requests****
>
>         8184          .            .   SMA outstanding allocations****
>
>     46354320          .            .   SMA outstanding bytes****
>
> 12051521527          .            .   SMA bytes allocated****
>
> 12005167207          .            .   SMA bytes free****
>
>       357190         1.98         0.87 SMS allocator requests****
>
>            0          .            .   SMS outstanding allocations****
>
>            0          .            .   SMS outstanding bytes****
>
>    135529138          .            .   SMS bytes allocated****
>
>    135529138          .            .   SMS bytes freed****
>
>      4744578        20.80        11.55 Backend requests made****
>
>            1         0.00         0.00 N vcl total****
>
>            1         0.00         0.00 N vcl available****
>
>       240460          .            .   N total active purges****
>
>       353239         1.98         0.86 N new purges added****
>
>       112779         0.99         0.27 N old purges deleted****
>
>       510753         0.99         1.24 N objects tested****
>
>     32284561       412.94        78.61 N regexps tested against****
>
>       155686         0.99         0.38 N duplicate purges removed****
>
> ** **
>
> ** **
>
> Thanks for any help,****
>
> Connor Walls ****
>
> ** **
>
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>



-- 
Stig Bakken
CTO, Zedge.net - free your phone!
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