title: Track Virtual Memory System Writing to Disk
name: mmwriteback.stp
version: 1.0
author: Red Hat
keywords: memory
subsystem: memory
status: experimental
exit: user-controlled
output: sorted-list
scope: system-wide
description: The mmwriteback.stp script uses the virtual memory tracepoints available in some kernels to report all of the file writebacks that occur form kupdate, pdflush and kjournald while the script is running.  It's useful in determining where writes are coming from on a supposedly idle system that is experiencing unexpected IO.
test_support: (stap -l 'kernel.trace("balance_dirty_pages")' || stap -l 'kernel.trace("mm_balancedirty_writeout")' || stap -l 'kernel.trace("mm_pdflush_bgwriteout")') && (stap -l 'kernel.trace("writeback_pages_written")' || stap -l 'kernel.trace("mm_pdflush_kupdate")') && (stap -l 'kernel.trace("mm_vmscan_writepage")' || stap -l 'kernel.trace("mm_pagereclaim_pgout")')
test_check: stap -p4 mmwriteback.stp
test_installcheck: stap mmwriteback.stp -c "sleep 0.2"