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Currently, when afs_ShakeLooseVCaches runs osi_TryEvictVCache, we check if osi_TryEvictVCache slept (i.e. dropped afs_xvcache/GLOCK). If we sleep over 100 times, then we stop trying to evict vcaches and return. If we have recently accessed a lot of AFS files, this limitation can severely reduce our ability to keep our number of vcaches limited to a reasonable size. For example: Say a Linux client runs a process that quickly accesses 1 million files (a simple 'find' command) and then does nothing else. A few minutes later, afs_ShakeLooseVCaches is run, but since all of the newly accessed vcaches have dentries attached to them, we will sleep on each one in order to try to prune the attached dentries. This means that afs_ShakeLooseVCaches will evict 100 vcaches, and then return, leaving us with still almost 1 million vcaches. This will happen repeatedly until afs_ShakeLooseVCaches finally works its way through all of the vcaches (which takes quite a while, if we only clear 100 at once), or the dentries get pruned by other means (such as, if Linux evicts them due to memory pressure). The limit of 100 sleeps was originally added in commit 29277d96 (newvcache-dont-spin-20060128), but the current effect of it was largely introduced in commit 9be76c0d (Refactor afs_NewVCache). It exists to ensure that afs_ShakeLooseVCaches doesn't take forever to run, but the limit of 100 sleeps may seem quite low, especially if those 100 sleeps run very quickly. To avoid the situation described above, instead of limiting afs_ShakeLooseVCaches based on a fixed number of sleeps, limit it based on how long we've been running, and set an arbitrary limit of roughly 3 seconds. Only check how long we've been running after 100 sleeps like before, so we're not constantly checking the time while running. Log a new warning if we exit afs_ShakeLooseVCaches prematurely if we've been running for too long, to help indicate what is going on. Reviewed-on: https://gerrit.openafs.org/14254 Reviewed-by: Cheyenne Wills <cwills@sinenomine.net> Tested-by: BuildBot <buildbot@rampaginggeek.com> Reviewed-by: Benjamin Kaduk <kaduk@mit.edu> (cherry picked from commit cd65475e95e25c8e7071e099a682bdcc03d2cce1) Change-Id: I6c8e440a3c4dec5e6d769f40d9638a3edc6ad333 Reviewed-on: https://gerrit.openafs.org/15536 Reviewed-by: Andrew Deason <adeason@sinenomine.net> Tested-by: BuildBot <buildbot@rampaginggeek.com> Reviewed-by: Marcio Brito Barbosa <mbarbosa@sinenomine.net> Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>
AFS is a distributed file system that enables users to share and access all of the files stored in a network of computers as easily as they access the files stored on their local machines. The file system is called distributed for this exact reason: files can reside on many different machines, but are available to users on every machine. OpenAFS 1.0 was originally released by IBM under the terms of the IBM Public License 1.0 (IPL10). For details on IPL10 see the LICENSE file in this directory. The current OpenAFS distribution is licensed under a combination of the IPL10 and many other licenses as granted by the relevant copyright holders. The LICENSE file in this directory contains more details, thought it is not a comprehensive statement. See INSTALL for information about building and installing OpenAFS on various platforms. See CODING for developer information and guidelines. See NEWS for recent changes to OpenAFS.