On 08/02/12 12:51, Rob Thurlow wrote:
On 8/1/12 4:53 PM, Mike Gerdts wrote:
Is it known and/or expected that nfs:/// repos perform *much* worse than
http:// repos?
Certainly; small I/Os and high latency kill NFS. On AK builds,
we get seriously spanked by using remote repos for image creation,
taking a build from 15 minutes to 3 hours unless the cache is warm.
If the necessary files can get staged into cache in a more efficient
way, something better might happen.
Agreed. What is it about the way that pkg accesses file repos that makes it so
much slower than http repos?
Each method seems to look to see if various files are there and get some
attributes (stat(2) or http HEAD) and need to transfer the files that are not
already present locally. Last time I checked, http and nfs packets go across
the wire at about the same speed. I think that NFS packets actually carry less
protocol baggage with the requests and returned data, so they should go a tiny
bit faster only because they should be a tiny bit smaller.
This leads me to think that pkg is doing a lot of unnecessary file system
operations such as multiple stat calls on the same file or calling stat before
trying to open a file. If file-based repos are intended to just be a
convenience for developers, perhaps this isn't an issue. If file-based repos
are intended to be used with NFS in global enterprises, this performance
disparity deserves attention.
--
Mike Gerdts
Solaris Core OS / Zones http://blogs.oracle.com/zoneszone/
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