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Posted to users@trafficserver.apache.org by David Carlin <dc...@yahoo-inc.com> on 2012/06/04 22:29:01 UTC
HostDB sizing
Is there a good rule of thumb for how to set
proxy.config.hostdb.storage_size as you increase the value of
proxy.config.hostdb.size?
It used to be that for values of proxy.config.hostdb.size above 200,000
you increase the storage_size variable by at least 44 bytes per entry.
However, I thought I read on IRC a few weeks back that this is no longer
the case as the data structure has changed.
Re: HostDB sizing
Posted by Leif Hedstrom <zw...@apache.org>.
On 6/4/12 2:29 PM, David Carlin wrote:
> Is there a good rule of thumb for how to set
> proxy.config.hostdb.storage_size as you increase the value of
> proxy.config.hostdb.size?
>
> It used to be that for values of proxy.config.hostdb.size above 200,000
> you increase the storage_size variable by at least 44 bytes per entry.
> However, I thought I read on IRC a few weeks back that this is no longer
> the case as the data structure has changed.
>
I believe the code here is a wild guess at best, but we have
virtual size_t estimated_heap_bytes_per_entry() const { return
sizeof(HostDBInfo) * 2; }
I seem to have changed that some time ago (3e1a81ab). :) In any case,
that would be
(gdb) print sizeof(HostDBInfo)
$1 = 80
There's also some overhead for other stuff, so, ~200 bytes / seems
plausible. I believe the 44 bytes -> 80 bytes is the change to IPv6.
Maybe the multiplier of 2x is overly pessimistic, I honestly don't know
:-/. This code needs to be rewritten anyways.
Cheers,
-- Leif