From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Stancek Date: Wed, 18 Dec 2019 04:24:51 -0500 (EST) Subject: [LTP] [PATCH RFC] sync_file_range02: remove the toplimit of write back In-Reply-To: <20191218082826.25083-1-liwang@redhat.com> References: <20191218082826.25083-1-liwang@redhat.com> Message-ID: <2104821569.17247635.1576661091375.JavaMail.zimbra@redhat.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: ltp@lists.linux.it ----- Original Message ----- > " The test's assumptions are fundamentally false; it thinks it can look > at IO counters (tst_dev_bytes_written) for a disk before and after a > system call, and attribute all of the IO seen to the system call that > was made - this isn't necessarily correct. Other processes may generate > IO in the background. We create our own block device, so there shouldn't be other processes writing to it. > ext4 defers a lot of IO on a freshly made filesystem to the kernel - > for example it will initialize the journal and inode tables after the > mount Journal was my guess as well. > Let's remove the toplimit of write back, and think as long as we synced > at least the expected amount, the test passes. The +10% limit seems > arbitrary. I think this is reasonable approach until we find better way to measure what was synced. Acked-by: Jan Stancek