Date: Wed, 15 Nov 2023 18:00:23 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 275063] kernel using 100% CPU in arc_prune Message-ID: <bug-275063-227-0ixum3Qv8s@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-275063-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=275063 --- Comment #3 from Martin Birgmeier <d8zNeCFG@aon.at> --- Just for information: This condition is triggered reliably as follows: - Create a sparse/compressed zvol: zfs create -o compress=on -s -V 20g hal.1/vdisks/903 - In a VM, slice & partition it in the old-fashioned way for carrying UFS filesystems: ada0s4a, ada0s4d (for / and /usr) - With the VM not running and from the host side, mount one of these filesystems - Run dd if=/dev/zero of=<mountpoint>/<tmpfile> until filesystem full; this is done to remove unallocated blocks because the sparse/compressed zvol discards blocks of zeros - The dd operation reliably triggers the arc_prune issue. The draining of taskq_zone (see PR 274698) is so slow that it would take many hours (on an otherwise completely idle system): [0]# vmstat -z | egrep '^ITEM|taskq' ; sleep 60 ; vmstat -z | egrep '^ITEM|taskq' ITEM SIZE LIMIT USED FREE REQ FAILSLEEP XDOMAIN taskq_zone: 192, 0, 2221547, 28456, 2980856, 0, 0, 0 ITEM SIZE LIMIT USED FREE REQ FAILSLEEP XDOMAIN taskq_zone: 192, 0, 2218760, 31243, 2980868, 0, 0, 0 [0]# A linear extrapolation results in about 13.3 hours. -- Martin -- You are receiving this mail because: You are the assignee for the bug.home | help
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