From 4d4972ed98a83a4b3a404f53782d5b351b8ef8cf Mon Sep 17 00:00:00 2001 From: Rich Ercolani <214141+rincebrain@users.noreply.github.com> Date: Fri, 12 Jan 2024 15:17:26 -0500 Subject: [PATCH] Stop wasting time on malloc in snprintf_zstd_header Profiling zdb -vvvvv on datasets with a lot of zstd blocks, we find ourselves spending quite a lot of time on malloc/free, because we allocate a 16M abd each call, and never free it, so we're leaking 16M per call as well. This seems sub-optimal. So let's just keep the buffer around and reuse it. Reviewed-by: Brian Behlendorf Reviewed-by: Rob Norris Signed-off-by: Rich Ercolani Closes #15721 --- cmd/zdb/zdb.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/cmd/zdb/zdb.c b/cmd/zdb/zdb.c index 3fc9fd2a9..70c85a87a 100644 --- a/cmd/zdb/zdb.c +++ b/cmd/zdb/zdb.c @@ -2360,7 +2360,7 @@ static void snprintf_zstd_header(spa_t *spa, char *blkbuf, size_t buflen, const blkptr_t *bp) { - abd_t *pabd; + static abd_t *pabd = NULL; void *buf; zio_t *zio; zfs_zstdhdr_t zstd_hdr; @@ -2391,7 +2391,8 @@ snprintf_zstd_header(spa_t *spa, char *blkbuf, size_t buflen, return; } - pabd = abd_alloc_for_io(SPA_MAXBLOCKSIZE, B_FALSE); + if (!pabd) + pabd = abd_alloc_for_io(SPA_MAXBLOCKSIZE, B_FALSE); zio = zio_root(spa, NULL, NULL, 0); /* Decrypt but don't decompress so we can read the compression header */