164 lines
5.3 KiB
Diff
164 lines
5.3 KiB
Diff
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From ba20326a937421c50a775907dc9ac726bb9a9b50 Mon Sep 17 00:00:00 2001
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From: Stefan Hajnoczi <stefanha@redhat.com>
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Date: Wed, 11 Sep 2013 16:42:35 +0200
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Subject: [PATCH] coroutine: add ./configure --disable-coroutine-pool
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The 'gthread' coroutine backend was written before the freelist (aka
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pool) existed in qemu-coroutine.c.
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This means that every thread is expected to exit when its coroutine
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terminates. It is not possible to reuse threads from a pool.
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This patch automatically disables the pool when 'gthread' is used. This
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allows the 'gthread' backend to work again (for example,
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tests/test-coroutine completes successfully instead of hanging).
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I considered implementing thread reuse but I don't want quirks like CPU
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affinity differences due to coroutine threads being recycled. The
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'gthread' backend is a reference backend and it's therefore okay to skip
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the pool optimization.
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Note this patch also makes it easy to toggle the pool for benchmarking
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purposes:
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./configure --with-coroutine-backend=ucontext \
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--disable-coroutine-pool
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Reported-by: Gabriel Kerneis <gabriel@kerneis.info>
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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Reviewed-by: Gabriel Kerneis <gabriel@kerneis.info>
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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(cherry picked from commit 70c60c089fdc6bf8a79324e492c13e8c08d55942)
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Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
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---
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configure | 24 ++++++++++++++++++++++++
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qemu-coroutine.c | 34 +++++++++++++++++++---------------
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2 files changed, 43 insertions(+), 15 deletions(-)
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diff --git a/configure b/configure
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index 18fa608..4cf672d 100755
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--- a/configure
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+++ b/configure
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@@ -235,6 +235,7 @@ guest_agent=""
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want_tools="yes"
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libiscsi=""
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coroutine=""
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+coroutine_pool=""
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seccomp=""
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glusterfs=""
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glusterfs_discard="no"
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@@ -871,6 +872,10 @@ for opt do
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;;
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--with-coroutine=*) coroutine="$optarg"
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;;
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+ --disable-coroutine-pool) coroutine_pool="no"
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+ ;;
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+ --enable-coroutine-pool) coroutine_pool="yes"
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+ ;;
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--disable-docs) docs="no"
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;;
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--enable-docs) docs="yes"
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@@ -1152,6 +1157,8 @@ echo " --disable-seccomp disable seccomp support"
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echo " --enable-seccomp enables seccomp support"
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echo " --with-coroutine=BACKEND coroutine backend. Supported options:"
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echo " gthread, ucontext, sigaltstack, windows"
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+echo " --disable-coroutine-pool disable coroutine freelist (worse performance)"
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+echo " --enable-coroutine-pool enable coroutine freelist (better performance)"
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echo " --enable-glusterfs enable GlusterFS backend"
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echo " --disable-glusterfs disable GlusterFS backend"
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echo " --enable-gcov enable test coverage analysis with gcov"
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@@ -3240,6 +3247,17 @@ else
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esac
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fi
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+if test "$coroutine_pool" = ""; then
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+ if test "$coroutine" = "gthread"; then
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+ coroutine_pool=no
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+ else
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+ coroutine_pool=yes
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+ fi
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+fi
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+if test "$coroutine" = "gthread" -a "$coroutine_pool" = "yes"; then
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+ error_exit "'gthread' coroutine backend does not support pool (use --disable-coroutine-pool)"
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+fi
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+
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##########################################
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# check if we have open_by_handle_at
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@@ -3605,6 +3623,7 @@ echo "libiscsi support $libiscsi"
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echo "build guest agent $guest_agent"
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echo "seccomp support $seccomp"
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echo "coroutine backend $coroutine"
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+echo "coroutine pool $coroutine_pool"
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echo "GlusterFS support $glusterfs"
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echo "virtio-blk-data-plane $virtio_blk_data_plane"
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echo "gcov $gcov_tool"
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@@ -3954,6 +3973,11 @@ if test "$rbd" = "yes" ; then
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fi
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echo "CONFIG_COROUTINE_BACKEND=$coroutine" >> $config_host_mak
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+if test "$coroutine_pool" = "yes" ; then
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+ echo "CONFIG_COROUTINE_POOL=1" >> $config_host_mak
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+else
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+ echo "CONFIG_COROUTINE_POOL=0" >> $config_host_mak
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+fi
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if test "$open_by_handle_at" = "yes" ; then
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echo "CONFIG_OPEN_BY_HANDLE=y" >> $config_host_mak
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diff --git a/qemu-coroutine.c b/qemu-coroutine.c
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index 423430d..4708521 100644
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--- a/qemu-coroutine.c
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+++ b/qemu-coroutine.c
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@@ -30,15 +30,17 @@ static unsigned int pool_size;
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Coroutine *qemu_coroutine_create(CoroutineEntry *entry)
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{
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- Coroutine *co;
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-
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- qemu_mutex_lock(&pool_lock);
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- co = QSLIST_FIRST(&pool);
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- if (co) {
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- QSLIST_REMOVE_HEAD(&pool, pool_next);
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- pool_size--;
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+ Coroutine *co = NULL;
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+
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+ if (CONFIG_COROUTINE_POOL) {
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+ qemu_mutex_lock(&pool_lock);
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+ co = QSLIST_FIRST(&pool);
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+ if (co) {
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+ QSLIST_REMOVE_HEAD(&pool, pool_next);
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+ pool_size--;
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+ }
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+ qemu_mutex_unlock(&pool_lock);
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}
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- qemu_mutex_unlock(&pool_lock);
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if (!co) {
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co = qemu_coroutine_new();
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@@ -51,15 +53,17 @@ Coroutine *qemu_coroutine_create(CoroutineEntry *entry)
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static void coroutine_delete(Coroutine *co)
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{
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- qemu_mutex_lock(&pool_lock);
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- if (pool_size < POOL_MAX_SIZE) {
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- QSLIST_INSERT_HEAD(&pool, co, pool_next);
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- co->caller = NULL;
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- pool_size++;
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+ if (CONFIG_COROUTINE_POOL) {
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+ qemu_mutex_lock(&pool_lock);
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+ if (pool_size < POOL_MAX_SIZE) {
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+ QSLIST_INSERT_HEAD(&pool, co, pool_next);
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+ co->caller = NULL;
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+ pool_size++;
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+ qemu_mutex_unlock(&pool_lock);
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+ return;
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+ }
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qemu_mutex_unlock(&pool_lock);
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- return;
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}
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- qemu_mutex_unlock(&pool_lock);
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qemu_coroutine_delete(co);
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}
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