- Avoid creating too large iovecs in multiwrite merge (#559717)

- Don't try to set max_kernel_pages during ksm init on newer kernels
    (#558281)
- Add logfile options for ksmtuned debug.

ksm.init

@@ -40,8 +40,10 @@ default_max_kernel_pages () {
 
 start() {
     echo -n $"Starting $prog: "
-    KSM_MAX_KERNEL_PAGES=${KSM_MAX_KERNEL_PAGES:-`default_max_kernel_pages`}
-    echo $KSM_MAX_KERNEL_PAGES > /sys/kernel/mm/ksm/max_kernel_pages
+    if [ -f /sys/kernel/mm/ksm/max_kernel_pages ]; then
+        KSM_MAX_KERNEL_PAGES=${KSM_MAX_KERNEL_PAGES:-`default_max_kernel_pages`}
+        echo $KSM_MAX_KERNEL_PAGES > /sys/kernel/mm/ksm/max_kernel_pages
+    fi
     echo 1 > /sys/kernel/mm/ksm/run
     RETVAL=$?
     [ $RETVAL = 0 ] && success $"$prog startup" || failure $"$prog startup"

ksmtuned

@@ -21,6 +21,14 @@ if [ -f /etc/ksmtuned.conf ]; then
     . /etc/ksmtuned.conf
 fi
 
+debug() {
+    if [ -n "$DEBUG" ]; then
+        s="`/bin/date`: $*"
+        [ -n "$LOGFILE" ] && echo "$s" >> "$LOGFILE" || echo "$s"
+    fi
+}
+
+
 KSM_MONITOR_INTERVAL=${KSM_MONITOR_INTERVAL:-60}
 KSM_NPAGES_BOOST=${KSM_NPAGES_BOOST:-300}
 KSM_NPAGES_DECAY=${KSM_NPAGES_DECAY:--50}
@@ -35,17 +43,17 @@ KSM_THRES_COEF=${KSM_THRES_COEF:-20}
 KSM_THRES_CONST=${KSM_THRES_CONST:-2048}
 
 total=`awk '/^MemTotal:/ {print $2}' /proc/meminfo`
-[ -n "$DEBUG" ] && echo total $total
+debug total $total
 
 npages=0
 sleep=$[KSM_SLEEP_MSEC * 16 * 1024 * 1024 / total]
 [ $sleep -le 10 ] && sleep=10
-[ -n "$DEBUG" ] && echo sleep $sleep
+debug sleep $sleep
 thres=$[total * KSM_THRES_COEF / 100]
 if [ $KSM_THRES_CONST -gt $thres ]; then
     thres=$KSM_THRES_CONST
 fi
-[ -n "$DEBUG" ] && echo thres $thres
+debug thres $thres
 
 KSMCTL () {
     case x$1 in
@@ -89,22 +97,22 @@ adjust () {
     local free committed
     free=`free_memory`
     committed=`committed_memory`
-    [ -n "$DEBUG" ] && echo committed $committed free $free
+    debug committed $committed free $free
     if [ $[committed + thres] -lt $total -a $free -gt $thres ]; then
         KSMCTL stop
-        [ -n "$DEBUG" ] && echo "$[committed + thres] < $total and free > $thres, stop ksm"
+        debug "$[committed + thres] < $total and free > $thres, stop ksm"
         return 1
     fi
-    [ -n "$DEBUG" ] && echo "$[committed + thres] > $total, start ksm"
+    debug "$[committed + thres] > $total, start ksm"
     if [ $free -lt $thres ]; then
         npages=`increase_npages $KSM_NPAGES_BOOST`
-        [ -n "$DEBUG" ] && echo "$free < $thres, boost"
+        debug "$free < $thres, boost"
     else
         npages=`increase_npages $KSM_NPAGES_DECAY`
-        [ -n "$DEBUG" ] && echo "$free > $thres, decay"
+        debug "$free > $thres, decay"
     fi
     KSMCTL start $npages $sleep
-    [ -n "$DEBUG" ] && echo "KSMCTL start $npages $sleep"
+    debug "KSMCTL start $npages $sleep"
     return 0
 }
 

ksmtuned.conf

@@ -14,3 +14,8 @@
 
 # KSM_THRES_COEF=20
 # KSM_THRES_CONST=2048
+
+# uncomment the following if you want ksmtuned debug info
+
+# LOGFILE=/var/log/ksmtuned
+# DEBUG=1

qemu-v2-block-avoid-creating-too-large-iovecs-in-multiwrite_merge.patch

@@ -0,0 +1,41 @@
+If we go over the maximum number of iovecs support by syscall we get
+back EINVAL from the kernel which translate to I/O errors for the guest.
+
+Add a MAX_IOV defintion for platforms that don't have it.  For now we use
+the same 1024 define that's used on Linux and various other platforms,
+but until the windows block backend implements some kind of vectored I/O
+it doesn't matter.
+
+Signed-off-by: Christoph Hellwig <hch@lst.de>
+
+Index: qemu/block.c
+===================================================================
+--- qemu.orig/block.c	2010-01-26 10:59:39.757004445 +0100
++++ qemu/block.c	2010-01-26 11:01:38.056023231 +0100
+@@ -1689,6 +1689,10 @@ static int multiwrite_merge(BlockDriverS
+             merge = bs->drv->bdrv_merge_requests(bs, &reqs[outidx], &reqs[i]);
+         }
+ 
++        if (reqs[outidx].qiov->niov + reqs[i].qiov->niov + 1 > IOV_MAX) {
++            merge = 0;
++        }
++
+         if (merge) {
+             size_t size;
+             QEMUIOVector *qiov = qemu_mallocz(sizeof(*qiov));
+Index: qemu/qemu-common.h
+===================================================================
+--- qemu.orig/qemu-common.h	2010-01-26 14:41:40.894254285 +0100
++++ qemu/qemu-common.h	2010-01-26 14:42:27.267275698 +0100
+@@ -54,6 +54,10 @@ struct iovec {
+     void *iov_base;
+     size_t iov_len;
+ };
++/*
++ * Use the same value as Linux for now.
++ */
++#define IOV_MAX		1024
+ #else
+ #include <sys/uio.h>
+ #endif
+

qemu.spec

@@ -1,7 +1,7 @@
 Summary: QEMU is a FAST! processor emulator
 Name: qemu
 Version: 0.12.2
-Release: 4%{?dist}
+Release: 5%{?dist}
 # Epoch because we pushed a qemu-1.0 package
 Epoch: 2
 License: GPLv2+ and LGPLv2+ and BSD
@@ -35,6 +35,8 @@ Patch07: qemu-Move-virtio-serial-to-Makefile.objs.patch
 Patch08: qemu-virtio-serial-Use-MSI-vectors-for-port-virtqueues.patch
 Patch09: qemu-virtio-console-Rename-virtio-serial.c-back-to-virti.patch
 
+Patch10: qemu-v2-block-avoid-creating-too-large-iovecs-in-multiwrite_merge.patch
+
 
 BuildRoot: %{_tmppath}/%{name}-%{version}-%{release}-root-%(%{__id_u} -n)
 BuildRequires: SDL-devel zlib-devel which texi2html gnutls-devel cyrus-sasl-devel
@@ -232,6 +234,7 @@ such as kvmtrace and kvm_stat.
 %patch07 -p1
 %patch08 -p1
 %patch09 -p1
+%patch10 -p1
 
 %build
 # --build-id option is used fedora 8 onwards for giving info to the debug packages.
@@ -515,6 +518,11 @@ fi
 %{_mandir}/man1/qemu-img.1*
 
 %changelog
+* Thu Feb 04 2010 Justin M. Forbes <jforbes@redhat.com> - 2:0.12.2-5
+- Avoid creating too large iovecs in multiwrite merge (#559717)
+- Don't try to set max_kernel_pages during ksm init on newer kernels (#558281)
+- Add logfile options for ksmtuned debug.
+
 * Wed Jan 27 2010 Amit Shah <amit.shah@redhat.com> - 2:0.12.2-4
 - Remove build dependency on iasl now that we have seabios