On Wed, Aug 25, 2021 at 01:51:32AM +0000, Neeraj Singh via GitGitGadget wrote: > From: Neeraj Singh <neerajsi@xxxxxxxxxxxxx> > > When adding many objects to a repo with core.fsyncObjectFiles set to > true, the cost of fsync'ing each object file can become prohibitive. > > One major source of the cost of fsync is the implied flush of the > hardware writeback cache within the disk drive. Fortunately, Windows, > MacOS, and Linux each offer mechanisms to write data from the filesystem > page cache without initiating a hardware flush. > > This patch introduces a new 'core.fsyncObjectFiles = 2' option that > takes advantage of the bulk-checkin infrastructure to batch up hardware > flushes. Another interesting way to flush on linux would be the syncfs call, which syncs all files on a file system. Once you write more than handful or two of files that tends to win out over a batch of fsync calls.
