[EMAIL PROTECTED] wrote on Mon, 28 Jan 2008 16:38 -0600:
> Attached patch disables the handle ledger. For those not familiar, the
> handle ledger is an in-memory structure that maintains allocated handles
> for a given server. I'm disabling it because reading the entire database
> each time the server loads is extremely expensive for large filesystems.
> Instead of choosing a handle from the ledger, the patch picks one randomly.
> This means we have to deal with collisions now, but because of our large
> handle space, they only occur every 100 billion times or so.
>
> I didn't blow away the handle allocation code entirely...I just disabled
> the calls that we had been using to invoke the handle ledger, and added
> some functionality that picks a random handle from a given range. In the
> dspace code, I modified the create function to continue up to 32 times if a
> collision with an already existing handle occurs.
Great change. Never liked that myself either. Some comments.
> diff -u -a -p -r1.152 dbpf-dspace.c
> --- src/io/trove/trove-dbpf/dbpf-dspace.c 8 Nov 2007 21:48:22 -0000
> 1.152
> +++ src/io/trove/trove-dbpf/dbpf-dspace.c 28 Jan 2008 21:55:49 -0000
[..]
> + } while(ret != DB_NOTFOUND && ++attempts > MAX_HANDLE_ALLOC_ATTEMPTS);
Uh, maybe <.
[..]
> diff -u -a -p -r1.46 trove-handle-mgmt.c
> --- src/io/trove/trove-handle-mgmt/trove-handle-mgmt.c 15 Aug 2007
> 18:43:09 -0000 1.46
> +++ src/io/trove/trove-handle-mgmt/trove-handle-mgmt.c 28 Jan 2008
> 21:55:49 -0000
[..]
> +#ifdef TROVE_HANDLE_LEDGER_ENABLED
Just kill it for good. Too many ifdefs as it is.
> + rfd = open("/dev/urandom", O_RDONLY, 0);
> + if(rfd < 0)
> + {
> + return -PVFS_EINVAL;
> + }
Painted ourselves into a linux-specific corner here. Maybe have the
usual time() etc. srand option here too if open fails.
> + random_r(&trove_handle_random_data, &r1);
> + i = r1 % extent_array->extent_count;
May want a feature test for this. Not sure if POSIX has gotten
itself into all the OSes on which people may run servers.
> + if(sizeof(r1) == 4)
> + {
> + random_r(&trove_handle_random_data, &r2);
> + handle |= ((PVFS_handle)r2) << 32;
> + }
You declared r1 as int32_t. Of course the size will be 4.
-- Pete
_______________________________________________
Pvfs2-developers mailing list
[email protected]
http://www.beowulf-underground.org/mailman/listinfo/pvfs2-developers
