Date: Mon, 25 May 2009 03:41:40 +0000 (UTC) From: Kip Macy <kmacy@FreeBSD.org> To: src-committers@freebsd.org, svn-src-user@freebsd.org Subject: svn commit: r192717 - user/kmacy/releng_7_2_fcs/sys/kern Message-ID: <200905250341.n4P3feQA009653@svn.freebsd.org>
next in thread | raw e-mail | index | archive | help
Author: kmacy Date: Mon May 25 03:41:40 2009 New Revision: 192717 URL: http://svn.freebsd.org/changeset/base/192717 Log: eliminate one point of contention for the mnt lock by making mnt_opwritecount atomically updated Modified: user/kmacy/releng_7_2_fcs/sys/kern/vfs_vnops.c Modified: user/kmacy/releng_7_2_fcs/sys/kern/vfs_vnops.c ============================================================================== --- user/kmacy/releng_7_2_fcs/sys/kern/vfs_vnops.c Mon May 25 03:24:47 2009 (r192716) +++ user/kmacy/releng_7_2_fcs/sys/kern/vfs_vnops.c Mon May 25 03:41:40 2009 (r192717) @@ -929,7 +929,7 @@ vn_start_write(vp, mpp, flags) } if (flags & V_XSLEEP) goto unlock; - mp->mnt_writeopcount++; + atomic_add_int(&mp->mnt_writeopcount, 1); unlock: MNT_REL(mp); MNT_IUNLOCK(mp); @@ -999,19 +999,23 @@ vn_start_secondary_write(vp, mpp, flags) * now in effect. */ void -vn_finished_write(mp) - struct mount *mp; +vn_finished_write(struct mount *mp) { + int writeopcount; + if (mp == NULL) return; - MNT_ILOCK(mp); - mp->mnt_writeopcount--; - if (mp->mnt_writeopcount < 0) + + writeopcount = atomic_fetchadd_int(&mp->mnt_writeopcount, -1) - 1; + + if (writeopcount < 0) panic("vn_finished_write: neg cnt"); if ((mp->mnt_kern_flag & MNTK_SUSPEND) != 0 && - mp->mnt_writeopcount <= 0) + writeopcount <= 0) { + MNT_ILOCK(mp); wakeup(&mp->mnt_writeopcount); - MNT_IUNLOCK(mp); + MNT_IUNLOCK(mp); + } }
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200905250341.n4P3feQA009653>