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Wed, 23 Feb 2022 12:05:00 +0000 (GMT) Received: from localhost (unknown [9.43.68.5]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 23 Feb 2022 12:05:00 +0000 (GMT) Date: Wed, 23 Feb 2022 17:34:57 +0530 From: Ritesh Harjani To: Jan Kara Cc: linux-ext4@vger.kernel.org, Harshad Shirwadkar , "Theodore Ts'o" , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC 3/9] ext4: Add couple of more fast_commit tracepoints Message-ID: <20220223120457.a6mx3uufvainfi2n@riteshh-domain> References: <90608d31b7ad8500c33d875d3a7fa50e3456dc1a.1645558375.git.riteshh@linux.ibm.com> <20220223094057.53zcovnazrqwbngw@quack3.lan> <20220223101159.ekwbylvbmec5v35q@riteshh-domain> <20220223115313.3s73bu7p454bodvl@quack3.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220223115313.3s73bu7p454bodvl@quack3.lan> X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: mfiuBmmEeruvcLuHMfmnrzevTk-Oz7M4 X-Proofpoint-GUID: OZj7rKQW6lhngJSE81vl9WGJ0SrZQe5E X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.816,Hydra:6.0.425,FMLib:17.11.64.514 definitions=2022-02-23_03,2022-02-23_01,2022-02-23_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=43 lowpriorityscore=0 mlxscore=43 impostorscore=0 phishscore=0 adultscore=0 clxscore=1015 suspectscore=0 priorityscore=1501 mlxlogscore=12 bulkscore=0 malwarescore=0 spamscore=43 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2201110000 definitions=main-2202230068 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 22/02/23 12:53PM, Jan Kara wrote: > On Wed 23-02-22 15:41:59, Ritesh Harjani wrote: > > On 22/02/23 10:40AM, Jan Kara wrote: > > > On Wed 23-02-22 02:04:11, Ritesh Harjani wrote: > > > > This adds two more tracepoints for ext4_fc_track_template() & > > > > ext4_fc_cleanup() which are helpful in debugging some fast_commit issues. > > > > > > > > Signed-off-by: Ritesh Harjani > > > > > > So why is this more useful than trace_ext4_fc_track_range() and other > > > tracepoints? I don't think it provides any more information? What am I > > > missing? > > > > Thanks Jan for all the reviews. > > > > So ext4_fc_track_template() adds almost all required information > > (including the caller info) in this one trace point along with transaction tid > > which is useful for tracking issue similar to what is mentioned in Patch-9. > > > > (race with if inode is part of two transactions tid where jbd2 full commit > > may begin for txn n-1 while inode is still in sbi->s_fc_q[MAIN]) > > I understand commit tid is interesting but cannot we just add it to > tracepoints like trace_ext4_fc_track_range() directly? It would seem useful > to have it there and when it is there, the need for > ext4_fc_track_template() is not really big. I don't care too much but Yes make sense. Sure, I will look into adding this info to existing trace points then. With that I think trace_ext4_fc_track_template() won't be required. Will add those changes in V2. > this tracepoint looked a bit superfluous to me. > > > And similarly ext4_fc_cleanup() helps with that information about which tid > > completed and whether it was called from jbd2 full commit or from fast_commit. > > Yeah, that one is clear. Will retain trace_ext4_fc_cleanup() then. -ritesh > > Honza > -- > Jan Kara > SUSE Labs, CR