After a few hundred subvol threads start running, the inode cache starts
to thrash, and the log gets spammed with messages of the form:
"open_root_nocache <subvolid>: <path>"
Ideally there would be some way to schedule work to minimize inode
thrashing. Until that gets done, just silence the messages for now.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Tune the concurrency model to work a little better with large numbers
of subvols. This is much less than the full rewrite Bees desparately
needs, but it provides a marginal improvement until the new code is ready.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
With many threads it is inconvenient to reassemble the elided parts of
the dedup src/dst and scan filenames output. Simply output them
unconditionally, and balance the line lengths.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
This code has been #if 0 for a long time, and it seems unlikely it
will ever be useful in the future.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
If we lose a race and open the wrong file, we will not retry with the
next path if the file we opened had incompatible flags. We need to keep
trying paths until we open the correct file or run out of paths.
Fix by moving the inode flag check after the checks for file identity.
Output attributes in hex to be consistent with other attribute error
messages.
There is no need to report root and file paths separately in the error
message for incompatible flags because we have confirmed the identity of
the file before the incompatible flag error is detected. Other messages
in this loop still output root path and file_path separately because
the identity of 'rv' is unknown at the time these messages are emitted.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
If you have a lot of or a few big nocow files (like vm images) which
contain a lot of potential deduplication candidates, bees becomes
incredibly slow running through a lot "invalid operation" exceptions.
Let's just skip over such files to get more bang for the buck. I did no
regression testing as this patch seems trivial (and I cannot imagine any
pitfalls either). The process progresses much faster for me now.
BLOCK_SIZE_MIN_EXTENT_DEFRAG, BLOCK_SIZE_MIN_EXTENT_SPLIT, and others
are no longer used. Remove them.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Reads can block indefinitely due to bugs, low io priority, or poor
storage performance. Record the block origin data in the thread state
so we can see which reads are problematic.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Use () instead of [] when the respective end of the byte range touches
the beginning or end of the file. Also omit the '0' at beginning of
file.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
All testing so far incidates more crawlers go faster up to a limit
much larger than btrfs's performance limitations on subvols, even on
spinning rust. Remove the artificial constraint.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
perf blames the SEARCH_V2 ioctl wrapper for a lot of time spent in malloc.
Use a thread_local buffer for ioctl results, and reuse it between runs.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
We were holding weak refs until the next time the resource ID was used.
This is a bad thing if resource IDs are sparse (e.g. pointers or hashes)
because we'll never see an ID twice.
To fix, determine whether we released the last instance of a resource,
and if so, free its weak ref immediately.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Keep track of the locking thread so we can see why we are deadlocked
in gdb.
Use a handle type for locks based on shared_ptr. Change the handle type
name to flush out any non-auto local variables.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
In gcc 7+ warning: implicit-fallthrough has been added
In some places fallthrough is expectable, disable warning
Signed-off-by: Timofey Titovets <nefelim4ag@gmail.com>
Holding file FDs open for long periods of time delays inode destruction.
For very large files this can lead to excessive delays while bees dedups
data that will cease to be reachable.
Use the same workaround for file FDs (in the root_ino cache) that
is used for subvols (in the root cache): forcibly close all cached
FDs at regular intervals. The FD cache will reacquire FDs from files
that still have existing paths, and will abandon FDs from files that
no longer have existing paths. The non-existing-path case is not new
(bees has always been able to discover deleted inodes) so it is already
handled by existing code.
Fixes: https://github.com/Zygo/bees/issues/18
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Interesting things happen when blindly swapping the release-build CCFLAGS
with the debug-build commented-out CCFLAGS. None of these things that
happen are good.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
The bugs in other parts of the code have been identified and fixed,
so the overprotective locks around shared_ptr can be removed.
Keep the other improvements to the Resource class.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
This might improve performance on systems with more than 3 CPU cores...or
it might bring such a machine to its knees.
TODO: find out which of those two things happens.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Dedup was spending a lot of time waiting for the ioctl mutex while it
was held by non-dedup ioctls; however, when dedup finally locked the
mutex, its average run time was comparatively short and the variance
was low.
With the various workarounds and kernel fixes in place, FILE_EXTENT_SAME
and bees play well enough together that we can allow multiple threads
to do dedup at the same time. The extent bytenr lockset should be
sufficient to prevent undesirable results (i.e. dup data not removed,
or deadlocks on old kernels).
Remove the ioctl lock on dedup.
LOGICAL_INO and SEARCH_V2 (as used by BeesCrawl) remain under the ioctl
mutex because they can still have abitrarily large run times.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
This prevents two threads from attempting to dispose of the same physical
extent at the same time. This is a more precise exclusion than the
general lock on all tmpfiles.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
BeesRoots::crawl_state_erase may invoke BeesCrawl::~BeesCrawl, which
will do a join on its crawl thread, which might be trying to lock
BeesRoots::m_mutex, which is locked by crawl_state_erase at the time.
Fix this by creating an extra reference to the BeesCrawl object, then
releasing the lock on BeesRoots::m_mutex, then deleting the reference.
The BeesCrawl object may still call methods on BeesRoots, but the only
such method is BeesRoots::crawl_state_set_dirty, and that method has
no dependency on the erased BeesCrawl shared_ptr.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
This is yet another multi-threaded Bees experiment.
This time we are dividing the work by subvol: one thread is created to
process each subvol in the filesystem. There is no change in behavior
on filesystems containing only one subvol.
In order to avoid or mitigate the impact of kernel bugs and performance
issues, the btrfs ioctls FILE_EXTENT_SAME, SEARCH_V2, and LOGICAL_INO are
serialized. Only one thread may execute any of these ioctls at any time.
All three ioctls share a single lock.
In order to simplify the implementation, only one thread is permitted to
create a temporary file during one call to scan_one_extent. This prevents
multiple threads from racing to replace the same physical extent with
separate physical copies.
The single "crawl" thread is replaced by one "crawl_<root_number>"
for each subvol.
The crawl size is reduced from 4096 items to 1024. This reduces the
memory requirement per subvol and keeps the data in memory fresher.
It also increases the number of log messages, so turn some of them off.
TODO: Currently there is no configurable limit on the total number
of threads. The number of CPUs is used as an upper bound on the number
of active threads; however, we still have one thread per subvol even if
all most of the threads do is wait for locks.
TODO: Some of the single-threaded code is left behind until I make up
my mind about whether this experiment is successful.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
check_overflow() will invalidate iterators if it decides there are too
many cache entries.
If items are deleted from the cache, search for the inserted item again
to ensure the iterator is valid.
Increase size of timestamp to size_t.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
