On Wed, Mar 16, 2022 at 11:21:56AM -0700, Neeraj Singh wrote: > On Wed, Mar 16, 2022 at 12:31 AM Patrick Steinhardt <ps@xxxxxx> wrote: > > > > On Tue, Mar 15, 2022 at 09:30:54PM +0000, Neeraj Singh via GitGitGadget wrote: > > > From: Neeraj Singh <neerajsi@xxxxxxxxxxxxx> > > > diff --git a/Documentation/config/core.txt b/Documentation/config/core.txt > > > index 062e5259905..c041ed33801 100644 > > > --- a/Documentation/config/core.txt > > > +++ b/Documentation/config/core.txt > > > @@ -628,6 +628,11 @@ core.fsyncMethod:: > > > * `writeout-only` issues pagecache writeback requests, but depending on the > > > filesystem and storage hardware, data added to the repository may not be > > > durable in the event of a system crash. This is the default mode on macOS. > > > +* `batch` enables a mode that uses writeout-only flushes to stage multiple > > > + updates in the disk writeback cache and then a single full fsync to trigger > > > + the disk cache flush at the end of the operation. This mode is expected to > > > + be as safe as `fsync` on macOS for repos stored on HFS+ or APFS filesystems > > > + and on Windows for repos stored on NTFS or ReFS filesystems. > > > > This mode will not be supported by all parts of our stack that use our > > new fsync infra. So I think we should both document that some parts of > > the stack don't support batching, and say what the fallback behaviour is > > for those that don't. > > > > Can do. I'm hoping that you'll revive your batch-mode refs change too so that > we get batching across the ODB and Refs, which are the two data stores that > may receive many updates in a single Git command. Huh, I completely forgot that my previous implementation already had such a mechanism. I may have a go at it again, but it would take me a while given that I'll be OOO most of April. > This documentation > comment will read: > ``` > * `batch` enables a mode that uses writeout-only flushes to stage multiple > updates in the disk writeback cache and then does a single full fsync of > a dummy file to trigger the disk cache flush at the end of the operation. > Currently `batch` mode only applies to loose-object files. Other repository > data is made durable as if `fsync` was specified. This mode is expected to > be as safe as `fsync` on macOS for repos stored on HFS+ or APFS filesystems > and on Windows for repos stored on NTFS or ReFS filesystems. > ``` Reads good to me, thanks! Patrick
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