This avoids a really nasty race condition in our cache controler where
two concurrents could try to initialize cache on the same file.
This had two nasty effects: first shared map was purely leaked and erased
by the second one. And the private cache map, allocated on the first shared
cache map couldn't be freed and was leading to Mm BSOD (free in a middle of
a block).
This was often triggered while building ReactOS on ReactOS (with multi threads).
With that patch, I cannot crash anylonger while building ReactOS.
CORE-14634
In the lazy writer run, first post items that are queued for this.
Only then, start executing deferred writes if any.
If there were any, reschedule immediately a lazy writer run, to keep
Cc warm and to make it unqueue write faster in case of high IOs situation.
To make second lazy writer run happen faster, we keep our state active to
use short delay (1s) instead of standard idle (3s).
Recent changes seem to show that it's not
required to be exclusive on VACB to be able
to flush it.
This commit goes with f2c44aa and fixes the
last issues going with copying huge files.
There are no longer BSODs (be it in Mm or Cc).
I could, with 750MB RAM extract a 2GB file from
a 53MB archive and copy a 2,5GB file from a VBox
share to the disk. Note that writes are often
deferred, so if copy works, it's not that fast for now.
Note that it also brings some beloved behavior from
Windows: copy times are totally unreliable now when
writes are deferred. Little remaining times when
actively copying, high remaining times when deferred
writes in action. And goes between both... Sorry! ;-)
https://xkcd.com/612/
CORE-9696
CORE-11175
Same mechanism exists in Windows (even their Cc
is way different from ours...) where when Cc is
out of memory (in their case, out of VACB), we
will start scavenge old & unused VACB to free
some of the memory.
It's useful in case we're operating we big files
operations, we may run out of memory where to map
VACB for them, so start to scavenge VACB to free
some of that memory.
With this, I am able to install Qt 4.8.6 with 2,5GB of RAM,
scavenging acting when needed!
CORE-12081
CORE-14582
Adjusting refcount and enabling lazy-write for pinned
VACB makes it actually more efficient, often purging
data to disk, reducing memory stress for the system.
This is required for defering writes.
This commit unfortunately (?) reverts a previous revert.
CORE-12081
CORE-14582
CORE-14313
When no name is set in the file object, try to read the name
from the FCB. We only support FastFAT (ours) FCB for now.
This is clearly a hack, but for a kdbg command, so ;-)
It seems that on process killing, some VACB may be deleted while
still mapped. With current reference counting, they will actually
not be deleted, but leaked, and an ASSERT will be triggered.
CORE-14578
This has have several benefits for ReactOS Cc:
- It helps reducing potential deadlocks situations in Cc
- It speeds up ReactOS by reducing locks
- It gets us a bit closer to Windows VACB
CORE-14349
The avoids race conditions where attempts to read from disk to
not fully initialized VACB were performed.
Also, added more debug prints in such situations.
CORE-14349
This allows being consistent between newly created and looked up
so that VACB can always safely be released.
Should really help with reference issues.
CORE-14481
CORE-14480
CORE-14482
This fixes various bugs linked to VACB counting:
- VACB not released when it should be
- Reference count expectations not being accurate
For the record, VACB should always have at least a reference
count of 1, unless you are to free it and removed it from
any linked list.
This commit also adds a bunch of asserts that should
help triggering invalid reference counting.
It should also fix numerous ASSERT currently triggered and
may help fixing random behaviours in Cc.
CORE-14285
CORE-14401
CORE-14293
This avoids locking Cc for too long by trying to read-ahead data which
is already in cache.
We now will only schedule a read ahead if next read should bring us
to a new VACB (perhaps not in cache).
This notably fixes Inkscape setup which was slown down by read-ahead
due to continous 1 byte reads.
Thanks to Thomas for his help on this issue.
CORE-14395
Standard shared cache map provides space for a private cache map, do the same
and make it available for the first handle. It avoids two allocations in a row.
This halfplements CcScheduleReadAhead() which is responsible for finding the next reads
to perform given last read and previous reads. I made it very basic for now, at least
to test the whole process.
This also introduces the CcExpressWorkQueue in the lazy writer which is responsible
for dealing with read ahead items and which is dealt with before the regular queue.
In CcCopyData(), if read was fine, schedule read ahead so that it can happen in background
without the FSD to notice it! Also, update the read history so that scheduling as a
bit of data.
Implement (à la "old Cc" ;-)) CcPerformReadAhead() which is responsible for performing
the read. It's only to be called by the worker thread.
Side note on the modifications done in CcRosReleaseFileCache(). Private cache map
is tied to a handle. If it goes away, private cache map gets deleted. Read ahead
can run after the handle was closed (and thus, private cache map deleted), so
it is mandatory to always lock the master lock before accessing the structure in
read ahead or before deleting it in CcRosReleaseFileCache(). Otherwise, you'll
just break everything. You've been warned!
This commit also partly reverts f8b5d27.
CORE-14312
before the call to CcRosReleaseFileCache() which expects to have it to properly clean the file.
So, move deletion code to CcRosReleaseFileCache() so that he's the only one to handle private map.
Should hopefully fix all the recent buildbots issues (and the universe perhaps, who knows?)
This reverts BCB being lazy written when marked dirty.
We'll go back to this behavior when this part will have been reworked and stabilized.
CORE-14263
CORE-14279
CORE-14285
We get rid of the old iLazyWriterNotify event in favor of work items
that contain an event that lazy writer will set once its done.
To implement this, we rely on the newly introduced CcPostTickWorkQueue work queue
that will contain work items that are to be queued once lazy writer is done.
Move the CcWaitForCurrentLazyWriterActivity() implementation to the
lazy writer file, and reimplemented it using the new support mechanisms
Instead move to a threading model like the Windows one.
We'll queue several work items to be executed in a system thread (Cc worker)
when there are VACB that have been marked as dirty. Furthermore, some delay
will be observed before action to avoid killing the system with IOs.
This new threading model opens way for read ahead and write behind implementation.
Also, moved the initialization of the lazy writer to CcInitializeCacheManager()
it has nothing to do with views and shouldn't be initialized there.
Also, moved the lazy writer implementation to its own file.
Modified CcDeferWrite() and CcRosMarkDirtyVacb() to take into account the new threading model.
Introduced new functions:
- CcPostWorkQueue(): post an item to be handled by Cc worker and spawn a worker if required
- CcScanDpc(): called after some time (not to have lazy writer always running) to queue a lazy scan
- CcLazyWriteScan(): the lazy writer we used to have
- CcScheduleLazyWriteScan(): function to call when you want to start a lazy writer run. It will make a DPC after some time and queue execution
- CcWorkerThread(): the worker thread that will handle lazy write, read ahead, and so on
- CcUnpinDataForThread() only release VACB when the last BCB reference is gone. This avoids having a valid BCB with an invalid VACB
- CcRosMarkDirtyVacb() will only accept non-dirty VACB now. This avoids a major bug where a an already dirty VACB was over-dereferenced
- Thanks to previous point, simplify CcRosUnmapVacb(), CcRosReleaseVacb() implementation
- And only set VACB dirty once in CcSetDirtyPinnedData()
- Add a few sanity checks
With that I can again install ReactOS with 128MB RAM :-).
CORE-14263
CORE-14268
Namely, implement CcSetDirtyPageThreshold() and add support for it
in CcCanIWrite().
Also added my name in the headers of the few files I touched tonight.
CORE-14235
Namely, implement CcCanIWrite() (very basic, and likely wrong).
And implement CcDeferWrite() which will queue the write operation.
In CciLazyWriter() (which may be renamed CcWorkerThread() ;-)),
handle the queued write operations one by one. This is likely
not to be accurate, but, given we have only on FS supporting
this for now (NFS / RDBSS / Shares), this is OK.
CORE-14235
Experiment and MSDN tend to show that a dirty BCB is queued for lazy write.
This will do the job here!
Also, renamed CcRosMarkDirtyFile() which is more accurate, and added a new
function CcRosMarkDirtyVacb() which just takes a VACB as arg (expected locked)
and marks it dirty (using previous implementation). Make CcRosMarkDirtyFile()
use it.
CORE-14235
CcDirtyPageThreshold is not here to compute when you have to write,
but to know where you have to deny writes.
More commits to come in that direction!
CORE-14235
This removes the "modified page writer" thread in Mm that was regularly blindly
attempting to flush dirty pages to the disk.
Instead, this commit introduces a lazy writer that will monitor dirty pages count
and will flush them to disk when this count is above a threshold. The threshold is
computed on Cc init.
Compared to what was done previously, this lazy writer will only write down files
that are not marked as temporary.
The mechanisms involved in this lazy writer worker are well described in Windows
Internals 4th editions (constants are coming from it ;-)).
Also fixed a bad (and old!) bug in CcRosFlushDirtyPages() where target count could
be overflow and the function would spin forever while holding the VACBs lock. This is
mandatory as now lazy writer will call it with "random" values.
This also allows implementing CcWaitForCurrentLazyWriterActivity() :-).
Also renamed DirtyPageCount to its MS equivalent.
CORE-14235
This would affect reads/writes on large volumes where offset is higher than what a ULONG can hold.
This really nasty bug was hitting CcMapData() but also CcPinRead() (due to the nature of its implementation)
and both were returning garbage data under certain circumstances with Ext2Fsd.
This should (I hope!) help some other FSDs to work better in ROS.
CORE-12456
