On 08/16/2014 01:27 PM, Ivan Shapovalov wrote:
On Saturday 16 August 2014 at 10:23:08, Edward Shishkin wrote:
[...]
So I need to find a way to take rwsem in a read-biased mode... Any
advice is
accepted, including "give up with adding of yet another lock and go with
multiple transactions" :)
IMHO this is too complicated.
Why don't you want to grab, say, 20M per iteration?
It should work without any problems, just maintain a
counter of blocks allocated in the iteration..
I see it mostly like a "good to have" thing.
Nop, we discuss the reasonable implementation of the "must have" -
space reservation by the fitrim process..
When the system is under load,
FITRIM implemented in this "simple" way will be ineffective: it will miss
some blocks that are temporarily allocated (journal, etc.)
It will be perfectly discarded by the realtime discard
even though it is
theoretically possible to stop accepting new transactions, commit all existing
ones and perform discard while the system is artificially made idle, then
resume everything.
IMHO complicated and not need.
Anyway, missing 2 blocks per device is not critical.
So I've been trying to check if this is feasible. Looks like it isn't.
add the counter to the struct reiser4_context and
set it to zero at the beginning of every iteration.
use get_current_context() to access the counter.
Is it needed? The simple way is just a loop consisting of
- grab space
- allocate blocks forward from start position (initially 0) until end of
partition or limit reached
- update start position to `last allocated block + 1`
- put allocated space to the delete set
- mark for force-committing
- reiser4_txn_restart_current()
- if we've reached end of partition earlier, break, otherwise loop
Ok, it will also work (with more iterations, though),
well, let's do so..
Thanks,
Edward.
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