[DragonFlyBSD - Bug #2869] (Closed) hammer2 vs ccache: process hanging in chnmem state

[bugtracker-admin at leaf.dragonflybsd.org]

Issue #2869 has been updated by arcade at b1t.name.

Status changed from New to Closed

Upon further investigation I'm not sure this about ccache. ccache just helps the problem to manifest when there's a light but constant load on the disks.

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Bug #2869: hammer2 vs ccache: process hanging in chnmem state
http://bugs.dragonflybsd.org/issues/2869#change-12794

* Author: arcade at b1t.name
* Status: Closed
* Priority: Low
* Assignee: 
* Category: VFS subsystem
* Target version: 
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As I came from FreeBSD I already faced ccache a little over ZFS. When ccache is almost full it starts freeing space, and when it does so (on ZFS) it stucks in zio->* state for a long time perusing disk.

HAMMER2 behaves very bad in this case too:
 * we have free mem (like 600Mb);
 * ccache hangs in chnmem state;
 * disk is idle;
 * writes are heavily penalized, disk is slow;
 * console is full of:

Dec 18 22:16:25  kernel: Warning: cache_resolve: ncp '4cfd2287d50b992cca713202e76553-14712.manifest.rm..474328.XXXXXX' was unlinked
Dec 18 22:16:25  kernel: kern_rename: retry due to gen on: "4cfd2287d50b992cca713202e76553-14712.manifest.rm..474328.XXXXXX" -> "4cfd2287d50b992cca713202e76553-14712.manifest.rm..474377.XXXXXX"
Dec 18 22:16:25  kernel: Warning: cache_resolve: ncp '1afbb983f96488451e95ae9de240a4-87227.o.rm..474856.XXXXXX' was unlinked
Dec 18 22:16:25  kernel: kern_rename: retry due to gen on: "1afbb983f96488451e95ae9de240a4-87227.o.rm..474856.XXXXXX" -> "1afbb983f96488451e95ae9de240a4-87227.o.rm..474352.XXXXXX"
Dec 18 22:16:34  kernel: Warning: cache_resolve: ncp '8dc566823e04be58a3e8dab71cba61-68692.o.rm..474856.XXXXXX' was unlinked
Dec 18 22:16:34  kernel: kern_rename: retry due to gen on: "8dc566823e04be58a3e8dab71cba61-68692.o.rm..474856.XXXXXX" -> "8dc566823e04be58a3e8dab71cba61-68692.o.rm..474352.XXXXXX"
Dec 18 22:16:42  kernel: [diagnostic] cache_lock_shared: blocked on 0xffffffe10a97e430 00000001 "8dc566823e04be58a3e8dab71cba61-68692.d.rm..474856.XXXXXX"
Dec 18 22:16:42  kernel: [diagnostic] cache_lock: blocked on 0xffffffe108d04120 00000001 "efc494c16cb3457c3e959e4e44e51e-3156639.o.rm..474328.XXXXXX"
Dec 18 22:16:42  kernel: [diagnostic] cache_lock_shared: unblocked 8dc566823e04be58a3e8dab71cba61-68692.d.rm..474856.XXXXXX after 0 secs
Dec 18 22:16:42  kernel: [diagnostic] cache_lock: unblocked efc494c16cb3457c3e959e4e44e51e-3156639.o.rm..474328.XXXXXX after 8 secs
Dec 18 22:16:42  kernel: Warning: cache_resolve: ncp 'efc494c16cb3457c3e959e4e44e51e-3156639.o.rm..474328.XXXXXX' was unlinked
Dec 18 22:16:42  kernel: kern_rename: retry due to gen on: "efc494c16cb3457c3e959e4e44e51e-3156639.o.rm..474328.XXXXXX" -> "efc494c16cb3457c3e959e4e44e51e-3156639.o.rm..474377.XXXXXX"
Dec 18 22:16:47  kernel: Warning: cache_resolve: ncp 'c4bd7d4813f22726c2b45f6c8b7053-25838.manifest.rm..474856.XXXXXX' was unlinked
Dec 18 22:16:47  kernel: kern_rename: retry due to gen on: "c4bd7d4813f22726c2b45f6c8b7053-25838.manifest.rm..474856.XXXXXX" -> "c4bd7d4813f22726c2b45f6c8b7053-25838.manifest.rm..474352.XXXXXX"
Dec 18 22:17:01  kernel: Warning: cache_resolve: ncp '0ce9bbd7190adeccf1db7e582ff7d4-12275.manifest.rm..474352.XXXXXX' was unlinked




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