[ccache] Temporary Files vs NFS

Joel Rosdahl joel at rosdahl.net
Wed Apr 14 10:48:58 MDT 2010

On 2010-04-13 19:56, DATACOM - Samuel Lucas wrote:

> I'm considering using a shared cache over NFS, but I'm a bit concerned
> about creating the temporary files over NFS. Wouldn't the network become
> a performance bottleneck?

I haven't done any measurements of NFS-based caches myself, but it 
sounds probable that it will affect performance.

> [...] If we allow temporary files in local machine, would it create all
> temporary files (.i, etc) locally and then transfer in the network only
> the hash, speeding up the process?

In ccache 2.4, CCACHE_TEMPDIR needs to be on the same file system as 
CCACHE_DIR, but in 3.0pre0 that requirement is relaxed. In fact, it just 
occurred to me that CCACHE_TEMPDIR isn't needed anymore since it's only 
used to store truly temporary files that aren't moved into the cache. 
Unless I find any problem, I will remove the CCACHE_TEMPDIR setting and 
just use mkstemp(3) to create temporary files.

Please try ccache 3.0pre0 and set CCACHE_TEMPDIR to some local directory 
like /tmp and see if that improves performance.

-- Joel

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