diff options
Diffstat (limited to 'Documentation/vm/slub.txt')
| -rw-r--r-- | Documentation/vm/slub.txt | 22 |
1 files changed, 18 insertions, 4 deletions
diff --git a/Documentation/vm/slub.txt b/Documentation/vm/slub.txt index bb1f5c6e28b..b0c6d1bbb43 100644 --- a/Documentation/vm/slub.txt +++ b/Documentation/vm/slub.txt @@ -17,7 +17,7 @@ data and perform operation on the slabs. By default slabinfo only lists slabs that have data in them. See "slabinfo -h" for more options when running the command. slabinfo can be compiled with -gcc -o slabinfo Documentation/vm/slabinfo.c +gcc -o slabinfo tools/vm/slabinfo.c Some of the modes of operation of slabinfo require that slub debugging be enabled on the command line. F.e. no tracking information will be @@ -41,6 +41,9 @@ Possible debug options are P Poisoning (object and padding) U User tracking (free and alloc) T Trace (please only use on single slabs) + A Toggle failslab filter mark for the cache + O Switch debugging off for caches that would have + caused higher minimum slab orders - Switch all debugging off (useful if the kernel is configured with CONFIG_SLUB_DEBUG_ON) @@ -59,6 +62,14 @@ to the dentry cache with slub_debug=F,dentry +Debugging options may require the minimum possible slab order to increase as +a result of storing the metadata (for example, caches with PAGE_SIZE object +sizes). This has a higher liklihood of resulting in slab allocation errors +in low memory situations or if there's high fragmentation of memory. To +switch off debugging for such caches by default, use + + slub_debug=O + In case you forgot to enable debugging on the kernel command line: It is possible to enable debugging manually when the kernel is up. Look at the contents of: @@ -106,7 +117,7 @@ can be influenced by kernel parameters: slub_min_objects=x (default 4) slub_min_order=x (default 0) -slub_max_order=x (default 1) +slub_max_order=x (default 3 (PAGE_ALLOC_COSTLY_ORDER)) slub_min_objects allows to specify how many objects must at least fit into one slab in order for the allocation order to be acceptable. @@ -120,7 +131,10 @@ slub_min_objects. slub_max_order specified the order at which slub_min_objects should no longer be checked. This is useful to avoid SLUB trying to generate super large order pages to fit slub_min_objects of a slab cache with -large object sizes into one high order page. +large object sizes into one high order page. Setting command line +parameter debug_guardpage_minorder=N (N > 0), forces setting +slub_max_order to 0, what cause minimum possible order of slabs +allocation. SLUB Debug output ----------------- @@ -235,7 +249,7 @@ been overwritten. Here a string of 8 characters was written into a slab that has the length of 8 characters. However, a 8 character string needs a terminating 0. That zero has overwritten the first byte of the Redzone field. After reporting the details of the issue encountered the FIX SLUB message -tell us that SLUB has restored the Redzone to its proper value and then +tells us that SLUB has restored the Redzone to its proper value and then system operations continue. Emergency operations: |