From 370e009188ba90c3290b1479aa06ec98b66e140a Mon Sep 17 00:00:00 2001 From: Warner Losh Date: Mon, 13 Mar 2023 14:28:51 -0600 Subject: [PATCH] makefs: make msdos creation go fast Add missing brelse(bp). Without it the cache grows and we have a n^2 lookup. I'm not entirely sure why we read the block before we write it back out, since the only side effect of that is to allocate memory, clear the memory, read it in from disk, throw it away with the contents of the file being written out. We likely should just do a getblk() here instead, but even with all that, this takes the time it takes to create a 150MB msdos fs image down from 5 minutes to 30 seconds. Old: 317.663u 0.685s 5:18.34 100.0% 198+360k 0+19io 1009pf+0w New: 7.330u 23.841s 0:31.17 100.0% 198+360k 0+250522io 4pf+0w See code review for how we got this. tl;dr: netbsd move brelse into bwrite and we picked up msdos code after that, but not the move. That change should be picked up later. Sponsored by: Netflix Reviewed by: emaste MFC After: 1 day (13.2 is coming fast) Differential Revision: https://reviews.freebsd.org/D39025 --- usr.sbin/makefs/msdos/msdosfs_vnops.c | 1 + 1 file changed, 1 insertion(+) diff --git a/usr.sbin/makefs/msdos/msdosfs_vnops.c b/usr.sbin/makefs/msdos/msdosfs_vnops.c index 5bc9b495c58..c04ed6f742a 100644 --- a/usr.sbin/makefs/msdos/msdosfs_vnops.c +++ b/usr.sbin/makefs/msdos/msdosfs_vnops.c @@ -500,6 +500,7 @@ msdosfs_wfile(const char *path, struct denode *dep, fsnode *node) cpsize = MIN((nsize - offs), blsize - on); memcpy(bp->b_data + on, dat + offs, cpsize); bwrite(bp); + brelse(bp); offs += cpsize; }