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Date:      Sat, 28 Nov 2015 08:29:55 -0500 (EST)
From:      Rick Macklem <rmacklem@uoguelph.ca>
To:        FreeBSD FS <freebsd-fs@freebsd.org>
Subject:   should mutexes be uniquely named?
Message-ID:  <2132881382.109600978.1448717395325.JavaMail.zimbra@uoguelph.ca>

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Hi,

I think the patches I posted last week that add "-manage-gids" are about
ready for a commit to head.

However, there is one place in the code where I'm not sure which is better
to do:
--> The code replaces a single mutex with one for each hash list head (table
    entry).
    I currently use MTX_DUPOK and call them all the same thing.
or
    I could add a "lockname" field to the hash table enty structure and give
    each one a unique name (similar to what Garrett Wollman did in the kernel rpc).
    The only downside to this is 16bytes of storage for each hash table entry.
    (Admittedly, I don't think many sites would need to set the hash table size
     greater than a few thousand, so this isn't a lot of malloc()'d memory.)

So, what do you think. Should I add the code to make the mutex names unique?

Thanks in advance for any comments, rick
ps: The coding change is trivial. It just involves using more malloc()'d memory.



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