From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932612AbXBEOYt (ORCPT ); Mon, 5 Feb 2007 09:24:49 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932831AbXBEOYs (ORCPT ); Mon, 5 Feb 2007 09:24:48 -0500 Received: from mx1.redhat.com ([66.187.233.31]:49492 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932846AbXBEOYr (ORCPT ); Mon, 5 Feb 2007 09:24:47 -0500 Subject: [GFS2] Shrink gfs2_inode memory by half [29/54] From: Steven Whitehouse To: linux-kernel@vger.kernel.org Cc: cluster-devel@redhat.com In-Reply-To: <1170684425.11001.267.camel@quoit.chygwyn.com> References: <1170684425.11001.267.camel@quoit.chygwyn.com> Content-Type: text/plain Organization: Red Hat (UK) Ltd Date: Mon, 05 Feb 2007 14:32:51 +0000 Message-Id: <1170685971.11001.329.camel@quoit.chygwyn.com> Mime-Version: 1.0 X-Mailer: Evolution 2.2.2 (2.2.2-5) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org >>From 6be1a543bdaf360ab499e401ca5a0105a9923d75 Mon Sep 17 00:00:00 2001 From: Steven Whitehouse Date: Wed, 17 Jan 2007 15:33:23 +0000 Subject: [PATCH] [GFS2] Shrink gfs2_inode memory by half Here is something I spotted (while looking for something entirely different) the other day. Rather than using a completion in each and every struct gfs2_holder, this removes it in favour of hashed wait queues, thus saving a considerable amount of memory both on the stack (where a number of gfs2_holder structures are allocated) and in particular in the gfs2_inode which has 8 gfs2_holder structures embedded within it. As a result on x86_64 the gfs2_inode shrinks from 2488 bytes to 1912 bytes, a saving of 576 bytes per inode (no thats not a typo!). In actual practice we get a much better result than that since now that a gfs2_inode is under the 2048 byte barrier, we get two per 4k slab page effectively halving the amount of memory required to store gfs2_inodes. Signed-off-by: Steven Whitehouse diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index fb1960b..5341e03 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -19,6 +19,7 @@ #include #include #include +#include #include #include "gfs2.h" @@ -395,7 +396,6 @@ void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, unsigned flags, gh->gh_flags = flags; gh->gh_error = 0; gh->gh_iflags = 0; - init_completion(&gh->gh_wait); if (gh->gh_state == LM_ST_EXCLUSIVE) gh->gh_flags |= GL_LOCAL_EXCL; @@ -479,6 +479,29 @@ static void gfs2_holder_put(struct gfs2_holder *gh) kfree(gh); } +static void gfs2_holder_dispose_or_wake(struct gfs2_holder *gh) +{ + if (test_bit(HIF_DEALLOC, &gh->gh_iflags)) { + gfs2_holder_put(gh); + return; + } + clear_bit(HIF_WAIT, &gh->gh_iflags); + smp_mb(); + wake_up_bit(&gh->gh_iflags, HIF_WAIT); +} + +static int holder_wait(void *word) +{ + schedule(); + return 0; +} + +static void wait_on_holder(struct gfs2_holder *gh) +{ + might_sleep(); + wait_on_bit(&gh->gh_iflags, HIF_WAIT, holder_wait, TASK_UNINTERRUPTIBLE); +} + /** * rq_mutex - process a mutex request in the queue * @gh: the glock holder @@ -493,7 +516,9 @@ static int rq_mutex(struct gfs2_holder *gh) list_del_init(&gh->gh_list); /* gh->gh_error never examined. */ set_bit(GLF_LOCK, &gl->gl_flags); - complete(&gh->gh_wait); + clear_bit(HIF_WAIT, &gh->gh_flags); + smp_mb(); + wake_up_bit(&gh->gh_iflags, HIF_WAIT); return 1; } @@ -549,7 +574,7 @@ static int rq_promote(struct gfs2_holder *gh) gh->gh_error = 0; set_bit(HIF_HOLDER, &gh->gh_iflags); - complete(&gh->gh_wait); + gfs2_holder_dispose_or_wake(gh); return 0; } @@ -573,10 +598,7 @@ static int rq_demote(struct gfs2_holder *gh) list_del_init(&gh->gh_list); gh->gh_error = 0; spin_unlock(&gl->gl_spin); - if (test_bit(HIF_DEALLOC, &gh->gh_iflags)) - gfs2_holder_put(gh); - else - complete(&gh->gh_wait); + gfs2_holder_dispose_or_wake(gh); spin_lock(&gl->gl_spin); } else { gl->gl_req_gh = gh; @@ -684,6 +706,8 @@ static void gfs2_glmutex_lock(struct gfs2_glock *gl) gfs2_holder_init(gl, 0, 0, &gh); set_bit(HIF_MUTEX, &gh.gh_iflags); + if (test_and_set_bit(HIF_WAIT, &gh.gh_iflags)) + BUG(); spin_lock(&gl->gl_spin); if (test_and_set_bit(GLF_LOCK, &gl->gl_flags)) { @@ -691,11 +715,13 @@ static void gfs2_glmutex_lock(struct gfs2_glock *gl) } else { gl->gl_owner = current; gl->gl_ip = (unsigned long)__builtin_return_address(0); - complete(&gh.gh_wait); + clear_bit(HIF_WAIT, &gh.gh_iflags); + smp_mb(); + wake_up_bit(&gh.gh_iflags, HIF_WAIT); } spin_unlock(&gl->gl_spin); - wait_for_completion(&gh.gh_wait); + wait_on_holder(&gh); gfs2_holder_uninit(&gh); } @@ -774,6 +800,7 @@ restart: return; set_bit(HIF_DEMOTE, &new_gh->gh_iflags); set_bit(HIF_DEALLOC, &new_gh->gh_iflags); + set_bit(HIF_WAIT, &new_gh->gh_iflags); goto restart; } @@ -908,12 +935,8 @@ static void xmote_bh(struct gfs2_glock *gl, unsigned int ret) gfs2_glock_put(gl); - if (gh) { - if (test_bit(HIF_DEALLOC, &gh->gh_iflags)) - gfs2_holder_put(gh); - else - complete(&gh->gh_wait); - } + if (gh) + gfs2_holder_dispose_or_wake(gh); } /** @@ -999,12 +1022,8 @@ static void drop_bh(struct gfs2_glock *gl, unsigned int ret) gfs2_glock_put(gl); - if (gh) { - if (test_bit(HIF_DEALLOC, &gh->gh_iflags)) - gfs2_holder_put(gh); - else - complete(&gh->gh_wait); - } + if (gh) + gfs2_holder_dispose_or_wake(gh); } /** @@ -1105,8 +1124,7 @@ static int glock_wait_internal(struct gfs2_holder *gh) if (gh->gh_flags & LM_FLAG_PRIORITY) do_cancels(gh); - wait_for_completion(&gh->gh_wait); - + wait_on_holder(gh); if (gh->gh_error) return gh->gh_error; @@ -1162,6 +1180,8 @@ static void add_to_queue(struct gfs2_holder *gh) struct gfs2_holder *existing; BUG_ON(!gh->gh_owner); + if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags)) + BUG(); existing = find_holder_by_owner(&gl->gl_holders, gh->gh_owner); if (existing) { diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h index 9114851..a24c4af 100644 --- a/fs/gfs2/incore.h +++ b/fs/gfs2/incore.h @@ -128,6 +128,7 @@ enum { HIF_HOLDER = 6, HIF_FIRST = 7, HIF_ABORTED = 9, + HIF_WAIT = 10, }; struct gfs2_holder { @@ -140,7 +141,6 @@ struct gfs2_holder { int gh_error; unsigned long gh_iflags; - struct completion gh_wait; unsigned long gh_ip; }; -- 1.4.4.2