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McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 12/17] rcutorture: Print histogram of CB invocation at OOM time Date: Sun, 11 Nov 2018 12:20:22 -0800 X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181111201956.GA11935@linux.ibm.com> References: <20181111201956.GA11935@linux.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18111120-0052-0000-0000-00000354249F X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00010028; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000270; SDB=6.01116031; UDB=6.00578740; IPR=6.00896132; MB=3.00024115; MTD=3.00000008; XFM=3.00000015; UTC=2018-11-11 20:20:32 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18111120-0053-0000-0000-00005EBB30F0 Message-Id: <20181111202027.13585-12-paulmck@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-11-11_13:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1807170000 definitions=main-1811110194 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org One reason why a forward-progress test might fail would be if something prevented or delayed callback invocation. This commit therefore adds a callback-invocation histogram printout when OOM is reported to rcutorture. Signed-off-by: Paul E. McKenney --- kernel/rcu/rcutorture.c | 24 ++++++++++++++++-------- 1 file changed, 16 insertions(+), 8 deletions(-) diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index f28b88ecb47a..329f4fb13125 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -1631,6 +1631,20 @@ static bool rcu_fwd_emergency_stop; #define MIN_FWD_CBS_LAUNDERED 100 /* Number of counted CBs. */ static long n_launders_hist[2 * MAX_FWD_CB_JIFFIES / HZ]; +static void rcu_torture_fwd_cb_hist(void) +{ + int i; + int j; + + for (i = ARRAY_SIZE(n_launders_hist) - 1; i > 0; i--) + if (n_launders_hist[i] > 0) + break; + pr_alert("%s: Callback-invocation histogram:", __func__); + for (j = 0; j <= i; j++) + pr_cont(" %ds: %ld", j + 1, n_launders_hist[j]); + pr_cont("\n"); +} + /* Callback function for continuous-flood RCU callbacks. */ static void rcu_torture_fwd_cb_cr(struct rcu_head *rhp) { @@ -1718,7 +1732,6 @@ static void rcu_torture_fwd_prog_cr(void) unsigned long cver; unsigned long gps; int i; - int j; long n_launders; long n_launders_cb_snap; long n_launders_sa; @@ -1791,13 +1804,7 @@ static void rcu_torture_fwd_prog_cr(void) n_launders + n_max_cbs - n_launders_cb_snap, n_launders, n_launders_sa, n_max_gps, n_max_cbs, cver, gps); - for (i = ARRAY_SIZE(n_launders_hist) - 1; i > 0; i--) - if (n_launders_hist[i] > 0) - break; - pr_alert("Callback-invocation histogram:"); - for (j = 0; j <= i; j++) - pr_cont(" %ds: %ld", j + 1, n_launders_hist[j]); - pr_cont("\n"); + rcu_torture_fwd_cb_hist(); } } @@ -1809,6 +1816,7 @@ static void rcu_torture_fwd_prog_cr(void) static int rcutorture_oom_notify(struct notifier_block *self, unsigned long notused, void *nfreed) { + rcu_torture_fwd_cb_hist(); rcu_fwd_progress_check(1 + (jiffies - READ_ONCE(rcu_fwd_startat) / 2)); WRITE_ONCE(rcu_fwd_emergency_stop, true); return NOTIFY_OK; -- 2.17.1