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Wong" Cc: Dave Chinner , "linux-xfs@vger.kernel.org" , John Garry Subject: Re: [bug report] fstests generic/774 hang again Message-ID: References: <20260922002814.GK2705364@frogsfrogsfrogs> <20260925230329.GE2705364@frogsfrogsfrogs> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260925230329.GE2705364@frogsfrogsfrogs> X-ClientProxiedBy: TY4PR01CA0113.jpnprd01.prod.outlook.com (2603:1096:405:378::7) To SA1PR04MB10065.namprd04.prod.outlook.com (2603:10b6:806:4dd::14) X-Mailing-List: linux-xfs@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SA1PR04MB10065:EE_|LV2PR04MB994589:EE_ X-MS-Office365-Filtering-Correlation-Id: f2103d49-3911-47ff-8cae-08df302e32b0 WDCIPOUTBOUND: EOP-TRUE X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|23010399003|376014|1800799024|19092799006|366016|261021121427099003|56012099006|4143699003|11063799006|261009223027099003|18002099003|10067099003|22082099003; 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Wong wrote: [...] > > Yeah, I think you're on the right track with the dynamic tr_logcount > changes but I wonder if you want to constrain the max software atomic > write size so that we don't end up with gigantic chains that consume > significant portions of the log for a single write? > > Admittedly I see the multi-megabyte atomic write limits and marvel at > how far we've drifted from the original requirements. Darrick, thank you for the comments, and sorry for my slow response. Today, I found some time slot to try out max atomic write bytes capping. I took a look in your code snippet below, and was scratching my head. > > --D > > diff --git a/fs/xfs/libxfs/xfs_trans_resv.c b/fs/xfs/libxfs/xfs_trans_resv.c > index 1c20a7c27aa1bf..2e84544cd22a0a 100644 > --- a/fs/xfs/libxfs/xfs_trans_resv.c > +++ b/fs/xfs/libxfs/xfs_trans_resv.c > @@ -1473,6 +1473,10 @@ xfs_calc_max_atomic_write_fsblocks( > struct xfs_mount *mp) > { > const struct xfs_trans_res *resv = &M_RES(mp)->tr_atomic_ioend; > + const unsigned int max_log_bytes = > + XFS_FSB_TO_B(mp, mp->m_sb.sb_logblocks * 10 / 4); > + const unsigned int log_bytes_per_aw_block = > + (resv->tr_logres * resv->tr_logcount * 5) / 4; I wonder what the numbers in the two lines above mean. I think 5 means the number of transaction rolls required for an atomic write. But not sure about 10 and 4. May I ask you to elaborate them? Anyway, I applied this patch, and confirmed that awu_max reduced from 1024 to 64 in my test setup (4MiB to 256KiB). So, it looks working as expected.