[drupal-devel] Drupal.org cache statistics

K B kbahey at gmail.com
Thu May 26 20:03:08 UTC 2005


I assume that we are taking about Jeremy's patches.

Jeremy, you must have tried his new caching on kerneltrap.org. Did you
do any comparison of before and after to see how it fares? Does that
fit in Dries' findings?

Perhaps two different sites, two different usage patterns.

Don't know but it is weird.

On 5/26/05, Moshe Weitzman <weitzman at tejasa.com> wrote:
> Thanks Dries.
> 
> Wow. This is disappointing and a bit confusing. How can we interpret the
> seemingly contradictory changes described in 2 vs. 3?
> 
> I have to believe we can get more than 30% cache hits when our user base
> is 85% anonymous. Part of me wonders if we are not getting skewed
> results because of web crawlers. Thos crawlers spider all of our obscure
> pages and thus cause cache misses.
> 
> I agree that we need to work on the non cached case.
> 
> -moshe
> 
> Dries Buytaert wrote:
> > Hello world,
> >
> > november last year, I profiled drupal.org's cache observations.
> > Yesterday, Moshe asked to profile it again so we could evaluate the
> > usefulness of Jeremy's "loose caching" mechanism.
> >
> > The past 20 hours, I logged 93.000 unique page requests using the  patch
> > at http://buytaert.net/temporary/cache-statistics.patch.  Loose  caching
> > was enabled.
> >
> > Results:
> >
> > 1. Last year we found that authenticated users were responsible for
> > 15,8 % of all page views.  A year later, we see that authenticated
> > users are responsible for 14,9% of all page views.
> >
> > 2. Last year we found that only 27.9% of the page requests actually
> > benefited from the cache system.  That is, for more than 2/3th of the
> > page requests, we had to generate a page dynamically.  A year later,
> > using "loose caching" rather than "strict caching", we see that 30,7%
> > of the page requests benefit from the cache system.  Read: we still
> > have a lot of page cache misses! :(
> >
> > 3. Last year, we found that the cache got flushed once every 207 page
> > requests.  A year later, we observe that the cache got flushed once
> > every 190 page requests.
> >
> > We conclude that:
> >
> > 1. Loose caching does not significantly -- or not necessarily --
> > improve the behavior of drupal.org's page cache (though I'd like to
> > believe that it does when there are sudden traffic spikes/bursts).
> >
> > 2. When writing code, we can NOT assume that a page will benefit from
> > being cached.
> >
> > --
> > Dries Buytaert  ::  http://www.buytaert.net/
> >
> 
>



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