Ric Wheeler wrote:
Jeff Garzik wrote:
Jens Axboe wrote:
Another problem is that FLUSH_CACHE sucks. Really. And not just on
ext3/ordered, generally. Write a 50 byte file, fsync, flush cache and
wit for the world to finish. Pretty hard to teach people to use a nicer
fdatasync(), when the majority of the cost now becomes flushing the
cache of that 1TB drive you happen to have 8 partitions on. Good luck
with that.
(responding to an email way back near the start of the thread)
I emailed Microsoft about their proposal to add a WRITE BARRIER
command to ATA, documented at
http://www.t13.org/Documents/UploadedDocuments/docs2007/e07174r0-Write_Barrier_Command_Proposal.doc
The MSFT engineer said they were definitely still pursuing this proposal.
IMO we could look at this too, or perhaps come up with an alternate
proposal like FLUSH CACHE RANGE(s).
I agree that it is worth getting better mechanisms in place - the cache
flush is really primitive. Now we just need a victim to sit in on
T13/T10 standards meetings :-)
Heck, we could even do a prototype implementation with the help of Mark
Lord's sata_mv target mode support...
Jeff
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