On Tue, Apr 26, 2005 at 06:43:46PM +0200, Marc Olzheim wrote: > [changed cc: from standards@ back to stable@ again.] > > On Tue, Apr 26, 2005 at 12:25:49PM -0400, Brian Fundakowski Feldman wrote: > > You can assure that this happens in only two ways: > > > > 1. Make a complete copy of the data. This is what currently occurs: > > it gets stuffed into the buffer cache as the write happens. > > 2. Keep the data around synchronously -- by virtue of the write system > > call being used synchronously, the thread's VM context is around, > > and duplication need not occur. > > It seems as though FreeBSD 4.x either used 2) or does something wrong > indeed. Why would 2) be a problem on FreeBSD 5.x ? Can't the pages > written from be locked during the write, instead of copied internally ?
I'm still guessing that for whatever reason your writes on the FreeBSD 4.x NFS client are not using NFSv3/transactions. The second method I just now implemented; it works fine except for being slower since all data is acknowledged synchronously. Are you using one writev() instead of many writes so you can atomically write a large sparse data structure? If so, you will probably just have to cope with the lower performance than for reasonably-sized writes. If not: why are you trying to write it atomically? Just use multiple normal-sized write() calls. > Btw. running the writev program with 20 * 100 MB on UFS on a 512MB > FreeBSD 6-CURRENT system practicly locks the filesystem down _and_ > causes all processes to be swapped out in favor of the buffer cache. > 'top' however, doesnt' show a rise in BUF usage. > > On FreeBSD 4.x, the system performance as usual during the writev to > UFS. That's certainly not very optimal. I don't know anything about it, sorry. -- Brian Fundakowski Feldman \'[ FreeBSD ]''''''''''\ <> [EMAIL PROTECTED] \ The Power to Serve! \ Opinions expressed are my own. \,,,,,,,,,,,,,,,,,,,,,,\ _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "[EMAIL PROTECTED]"
