[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 <swhiteho@redhat.com>
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@ -19,6 +19,7 @@
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#include <linux/gfs2_ondisk.h>
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#include <linux/gfs2_ondisk.h>
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#include <linux/list.h>
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#include <linux/list.h>
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#include <linux/lm_interface.h>
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#include <linux/lm_interface.h>
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#include <linux/wait.h>
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#include <asm/uaccess.h>
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#include <asm/uaccess.h>
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#include "gfs2.h"
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#include "gfs2.h"
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@ -395,7 +396,6 @@ void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, unsigned flags,
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gh->gh_flags = flags;
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gh->gh_flags = flags;
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gh->gh_error = 0;
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gh->gh_error = 0;
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gh->gh_iflags = 0;
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gh->gh_iflags = 0;
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init_completion(&gh->gh_wait);
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if (gh->gh_state == LM_ST_EXCLUSIVE)
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if (gh->gh_state == LM_ST_EXCLUSIVE)
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gh->gh_flags |= GL_LOCAL_EXCL;
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gh->gh_flags |= GL_LOCAL_EXCL;
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@ -479,6 +479,29 @@ static void gfs2_holder_put(struct gfs2_holder *gh)
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kfree(gh);
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kfree(gh);
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}
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}
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static void gfs2_holder_dispose_or_wake(struct gfs2_holder *gh)
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{
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if (test_bit(HIF_DEALLOC, &gh->gh_iflags)) {
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gfs2_holder_put(gh);
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return;
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}
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clear_bit(HIF_WAIT, &gh->gh_iflags);
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smp_mb();
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wake_up_bit(&gh->gh_iflags, HIF_WAIT);
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}
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static int holder_wait(void *word)
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{
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schedule();
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return 0;
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}
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static void wait_on_holder(struct gfs2_holder *gh)
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{
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might_sleep();
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wait_on_bit(&gh->gh_iflags, HIF_WAIT, holder_wait, TASK_UNINTERRUPTIBLE);
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}
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/**
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/**
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* rq_mutex - process a mutex request in the queue
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* rq_mutex - process a mutex request in the queue
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* @gh: the glock holder
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* @gh: the glock holder
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@ -493,7 +516,9 @@ static int rq_mutex(struct gfs2_holder *gh)
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list_del_init(&gh->gh_list);
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list_del_init(&gh->gh_list);
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/* gh->gh_error never examined. */
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/* gh->gh_error never examined. */
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set_bit(GLF_LOCK, &gl->gl_flags);
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set_bit(GLF_LOCK, &gl->gl_flags);
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complete(&gh->gh_wait);
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clear_bit(HIF_WAIT, &gh->gh_flags);
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smp_mb();
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wake_up_bit(&gh->gh_iflags, HIF_WAIT);
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return 1;
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return 1;
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}
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}
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@ -549,7 +574,7 @@ static int rq_promote(struct gfs2_holder *gh)
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gh->gh_error = 0;
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gh->gh_error = 0;
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set_bit(HIF_HOLDER, &gh->gh_iflags);
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set_bit(HIF_HOLDER, &gh->gh_iflags);
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complete(&gh->gh_wait);
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gfs2_holder_dispose_or_wake(gh);
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return 0;
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return 0;
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}
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}
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@ -573,10 +598,7 @@ static int rq_demote(struct gfs2_holder *gh)
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list_del_init(&gh->gh_list);
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list_del_init(&gh->gh_list);
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gh->gh_error = 0;
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gh->gh_error = 0;
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spin_unlock(&gl->gl_spin);
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spin_unlock(&gl->gl_spin);
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if (test_bit(HIF_DEALLOC, &gh->gh_iflags))
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gfs2_holder_dispose_or_wake(gh);
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gfs2_holder_put(gh);
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else
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complete(&gh->gh_wait);
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spin_lock(&gl->gl_spin);
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spin_lock(&gl->gl_spin);
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} else {
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} else {
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gl->gl_req_gh = gh;
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gl->gl_req_gh = gh;
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@ -684,6 +706,8 @@ static void gfs2_glmutex_lock(struct gfs2_glock *gl)
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gfs2_holder_init(gl, 0, 0, &gh);
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gfs2_holder_init(gl, 0, 0, &gh);
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set_bit(HIF_MUTEX, &gh.gh_iflags);
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set_bit(HIF_MUTEX, &gh.gh_iflags);
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if (test_and_set_bit(HIF_WAIT, &gh.gh_iflags))
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BUG();
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spin_lock(&gl->gl_spin);
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spin_lock(&gl->gl_spin);
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if (test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
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if (test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
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@ -691,11 +715,13 @@ static void gfs2_glmutex_lock(struct gfs2_glock *gl)
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} else {
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} else {
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gl->gl_owner = current;
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gl->gl_owner = current;
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gl->gl_ip = (unsigned long)__builtin_return_address(0);
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gl->gl_ip = (unsigned long)__builtin_return_address(0);
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complete(&gh.gh_wait);
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clear_bit(HIF_WAIT, &gh.gh_iflags);
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smp_mb();
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wake_up_bit(&gh.gh_iflags, HIF_WAIT);
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}
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}
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spin_unlock(&gl->gl_spin);
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spin_unlock(&gl->gl_spin);
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wait_for_completion(&gh.gh_wait);
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wait_on_holder(&gh);
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gfs2_holder_uninit(&gh);
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gfs2_holder_uninit(&gh);
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}
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}
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@ -774,6 +800,7 @@ restart:
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return;
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return;
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set_bit(HIF_DEMOTE, &new_gh->gh_iflags);
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set_bit(HIF_DEMOTE, &new_gh->gh_iflags);
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set_bit(HIF_DEALLOC, &new_gh->gh_iflags);
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set_bit(HIF_DEALLOC, &new_gh->gh_iflags);
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set_bit(HIF_WAIT, &new_gh->gh_iflags);
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goto restart;
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goto restart;
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}
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}
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@ -908,12 +935,8 @@ static void xmote_bh(struct gfs2_glock *gl, unsigned int ret)
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gfs2_glock_put(gl);
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gfs2_glock_put(gl);
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if (gh) {
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if (gh)
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if (test_bit(HIF_DEALLOC, &gh->gh_iflags))
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gfs2_holder_dispose_or_wake(gh);
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gfs2_holder_put(gh);
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else
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complete(&gh->gh_wait);
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}
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}
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}
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/**
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/**
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@ -999,12 +1022,8 @@ static void drop_bh(struct gfs2_glock *gl, unsigned int ret)
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gfs2_glock_put(gl);
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gfs2_glock_put(gl);
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if (gh) {
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if (gh)
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if (test_bit(HIF_DEALLOC, &gh->gh_iflags))
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gfs2_holder_dispose_or_wake(gh);
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gfs2_holder_put(gh);
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else
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complete(&gh->gh_wait);
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}
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}
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}
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/**
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/**
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@ -1105,8 +1124,7 @@ static int glock_wait_internal(struct gfs2_holder *gh)
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if (gh->gh_flags & LM_FLAG_PRIORITY)
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if (gh->gh_flags & LM_FLAG_PRIORITY)
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do_cancels(gh);
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do_cancels(gh);
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wait_for_completion(&gh->gh_wait);
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wait_on_holder(gh);
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if (gh->gh_error)
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if (gh->gh_error)
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return gh->gh_error;
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return gh->gh_error;
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@ -1162,6 +1180,8 @@ static void add_to_queue(struct gfs2_holder *gh)
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struct gfs2_holder *existing;
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struct gfs2_holder *existing;
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BUG_ON(!gh->gh_owner);
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BUG_ON(!gh->gh_owner);
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if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
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BUG();
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existing = find_holder_by_owner(&gl->gl_holders, gh->gh_owner);
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existing = find_holder_by_owner(&gl->gl_holders, gh->gh_owner);
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if (existing) {
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if (existing) {
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@ -128,6 +128,7 @@ enum {
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HIF_HOLDER = 6,
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HIF_HOLDER = 6,
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HIF_FIRST = 7,
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HIF_FIRST = 7,
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HIF_ABORTED = 9,
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HIF_ABORTED = 9,
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HIF_WAIT = 10,
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};
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};
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struct gfs2_holder {
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struct gfs2_holder {
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@ -140,7 +141,6 @@ struct gfs2_holder {
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int gh_error;
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int gh_error;
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unsigned long gh_iflags;
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unsigned long gh_iflags;
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struct completion gh_wait;
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unsigned long gh_ip;
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unsigned long gh_ip;
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};
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};
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