Re: [RFC PATCH] object-file.c: batched disk flushes for stream_loose_object()
- From
Johannes Schindelin <johannes.schindelin@gmx.de>
- Date
- Jun 9, 2022, 09:30 UTC
- Message-ID
- <nycvar.QRO.7.76.6.2206091114070.349@tvgsbejvaqbjf.bet>
- In-Reply-To
- <20220609030530.51746-1-chiyutianyi@gmail.com>
Hi,
On Thu, 9 Jun 2022, Han Xin wrote:
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> Neeraj Singh[1] pointed out that if batch fsync is enabled, we should still > call prepare_loose_object_bulk_checkin() to potentially create the bulk checkin > objdir. > > 1. https://lore.kernel.org/git/7ba4858a-d1cc-a4eb-b6d6-4c04a5dd6ce7@gmail.com/ > > Signed-off-by: Han Xin <chiyutianyi@gmail.com>
I like a good commit message that is concise and yet has all the necessary information. Well done!
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> --- > object-file.c | 3 +++ > t/t5351-unpack-large-objects.sh | 15 ++++++++++++++- > 2 files changed, 17 insertions(+), 1 deletion(-) > > diff --git a/object-file.c b/object-file.c > index 2dd828b45b..3a1be74775 100644 > --- a/object-file.c > +++ b/object-file.c > @@ -2131,6 +2131,9 @@ int stream_loose_object(struct input_stream *in_stream, size_t len, > char hdr[MAX_HEADER_LEN]; > int hdrlen; > > + if (batch_fsync_enabled(FSYNC_COMPONENT_LOOSE_OBJECT)) > + prepare_loose_object_bulk_checkin(); > +
Makes sense.
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> /* Since oid is not determined, save tmp file to odb path. */ > strbuf_addf(&filename, "%s/", get_object_directory()); > hdrlen = format_object_header(hdr, sizeof(hdr), OBJ_BLOB, len); > diff --git a/t/t5351-unpack-large-objects.sh b/t/t5351-unpack-large-objects.sh > index 461ca060b2..a66a51f7df 100755 > --- a/t/t5351-unpack-large-objects.sh > +++ b/t/t5351-unpack-large-objects.sh > @@ -18,7 +18,10 @@ test_expect_success "create large objects (1.5 MB) and PACK" ' > test_commit --append foo big-blob && > test-tool genrandom bar 1500000 >big-blob && > test_commit --append bar big-blob && > - PACK=$(echo HEAD | git pack-objects --revs pack) > + PACK=$(echo HEAD | git pack-objects --revs pack) && > + git verify-pack -v pack-$PACK.pack | > + grep -E "commit|tree|blob" | > + sed -n -e "s/^\([0-9a-f]*\).*/\1/p" >obj-list
Here, I would recommend avoiding the pipe, to ensure that we would catch problems in the `verify-pack` invocation, and I think we can avoid the `grep` altogether:
git verify-pack -v pack-$PACK.pack >out && sed -n 's/^\([0-9a-f][0-9a-f]*\).*\(commit\|tree\|blob\)/\1/p' \ <out >obj-list
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> ' > > test_expect_success 'set memory limitation to 1MB' ' > @@ -45,6 +48,16 @@ test_expect_success 'unpack big object in stream' ' > test_dir_is_empty dest.git/objects/pack > ' > > +BATCH_CONFIGURATION='-c core.fsync=loose-object -c core.fsyncmethod=batch' > + > +test_expect_success 'unpack big object in stream (core.fsyncmethod=batch)' ' > + prepare_dest 1m && > + git $BATCH_CONFIGURATION -C dest.git unpack-objects <pack-$PACK.pack &&
I think the canonical way would be to use `test_config core.fsync ...`, but the presented way works, too.
> + test_dir_is_empty dest.git/objects/pack && > + git -C dest.git cat-file --batch-check="%(objectname)" <obj-list >current &&
Good. The `--batch-check="%(objectname)"` part forces `cat-file` to read the actual object.
> + cmp obj-list current > +'
My main question about this test case is whether it _actually_ verifies that the batch-mode `fsync()`ing took place.
I kind of had expected to see Trace2 enabled and a `grep` for `fsync/hardware-flush`. Do you think that would still make sense to add?
Thank you for working on the `fsync()` aspects of Git! Dscho
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> + > test_expect_success 'do not unpack existing large objects' ' > prepare_dest 1m && > git -C dest.git index-pack --stdin <pack-$PACK.pack && > -- > 2.36.1 > >