]> git.proxmox.com Git - qemu.git/commitdiff
native preadv/pwritev support (Christoph Hellwig)
authoraliguori <aliguori@c046a42c-6fe2-441c-8c8c-71466251a162>
Tue, 7 Apr 2009 18:43:28 +0000 (18:43 +0000)
committeraliguori <aliguori@c046a42c-6fe2-441c-8c8c-71466251a162>
Tue, 7 Apr 2009 18:43:28 +0000 (18:43 +0000)
This ties up the preadv/pwritev syscalls to qemu if they are declared in
unistd.h.  This is the case currently on at least NetBSD and OpenBSD and
will hopefully soon be the case on Linux.

Thanks to Blue Swirl and Gerd Hoffmann for the configure autodetection
of preadv/pwritev.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@7021 c046a42c-6fe2-441c-8c8c-71466251a162

block.c
configure
posix-aio-compat.c

diff --git a/block.c b/block.c
index 8a78f14ed549ba8d5c2dadd8535dd75629c69247..74d19ad288ed74f4f5a0afdc798f2136c8fa2f2f 100644 (file)
--- a/block.c
+++ b/block.c
@@ -1354,10 +1354,9 @@ static void bdrv_aio_bh_cb(void *opaque)
 {
     BlockDriverAIOCBSync *acb = opaque;
 
-    qemu_vfree(acb->bounce);
-
     if (!acb->is_write)
         qemu_iovec_from_buffer(acb->qiov, acb->bounce, acb->qiov->size);
+    qemu_vfree(acb->bounce);
     acb->common.cb(acb->common.opaque, acb->ret);
 
     qemu_aio_release(acb);
index 15b785604c53854578fb7a7c6f58711bb60d20d3..412828e9bae6d0b7346c2c7667846828e2bc5ddf 100755 (executable)
--- a/configure
+++ b/configure
@@ -1107,6 +1107,19 @@ if $cc $ARCH_CFLAGS -o $TMPE $TMPC > /dev/null 2> /dev/null ; then
   iovec=yes
 fi
 
+##########################################
+# preadv probe
+cat > $TMPC <<EOF
+#include <sys/types.h>
+#include <sys/uio.h>
+#include <unistd.h>
+int main(void) { preadv; }
+EOF
+preadv=no
+if $cc $ARCH_CFLAGS -o $TMPE $TMPC > /dev/null 2> /dev/null ; then
+  preadv=yes
+fi
+
 ##########################################
 # fdt probe
 if test "$fdt" = "yes" ; then
@@ -1221,6 +1234,7 @@ echo "AIO support       $aio"
 echo "Install blobs     $blobs"
 echo "KVM support       $kvm"
 echo "fdt support       $fdt"
+echo "preadv support    $preadv"
 
 if test $sdl_too_old = "yes"; then
 echo "-> Your SDL version is too old - please upgrade to have SDL support"
@@ -1522,6 +1536,9 @@ fi
 if test "$iovec" = "yes" ; then
   echo "#define HAVE_IOVEC 1" >> $config_h
 fi
+if test "$preadv" = "yes" ; then
+  echo "#define HAVE_PREADV 1" >> $config_h
+fi
 if test "$fdt" = "yes" ; then
   echo "#define HAVE_FDT 1" >> $config_h
   echo "FDT_LIBS=-lfdt" >> $config_mak
index 0eb77a50d3f79320f98cb4e69c5c6f47ed9001bf..c7fdac70b40b6cb50a0d4b2e7a9b4e62ab792d21 100644 (file)
@@ -33,6 +33,12 @@ static int cur_threads = 0;
 static int idle_threads = 0;
 static TAILQ_HEAD(, qemu_paiocb) request_list;
 
+#ifdef HAVE_PREADV
+static int preadv_present = 1;
+#else
+static int preadv_present = 0;
+#endif
+
 static void die2(int err, const char *what)
 {
     fprintf(stderr, "%s failed: %s\n", what, strerror(err));
@@ -87,6 +93,36 @@ static size_t handle_aiocb_ioctl(struct qemu_paiocb *aiocb)
        return ret;
 }
 
+#ifdef HAVE_PREADV
+
+static ssize_t
+qemu_preadv(int fd, const struct iovec *iov, int nr_iov, off_t offset)
+{
+    return preadv(fd, iov, nr_iov, offset);
+}
+
+static ssize_t
+qemu_pwritev(int fd, const struct iovec *iov, int nr_iov, off_t offset)
+{
+    return pwritev(fd, iov, nr_iov, offset);
+}
+
+#else
+
+static ssize_t
+qemu_preadv(int fd, const struct iovec *iov, int nr_iov, off_t offset)
+{
+    return -ENOSYS;
+}
+
+static ssize_t
+qemu_pwritev(int fd, const struct iovec *iov, int nr_iov, off_t offset)
+{
+    return -ENOSYS;
+}
+
+#endif
+
 /*
  * Check if we need to copy the data in the aiocb into a new
  * properly aligned buffer.
@@ -104,6 +140,29 @@ static int aiocb_needs_copy(struct qemu_paiocb *aiocb)
     return 0;
 }
 
+static size_t handle_aiocb_rw_vector(struct qemu_paiocb *aiocb)
+{
+    size_t offset = 0;
+    ssize_t len;
+
+    do {
+        if (aiocb->aio_type == QEMU_PAIO_WRITE)
+            len = qemu_pwritev(aiocb->aio_fildes,
+                               aiocb->aio_iov,
+                               aiocb->aio_niov,
+                               aiocb->aio_offset + offset);
+         else
+            len = qemu_preadv(aiocb->aio_fildes,
+                              aiocb->aio_iov,
+                              aiocb->aio_niov,
+                              aiocb->aio_offset + offset);
+    } while (len == -1 && errno == EINTR);
+
+    if (len == -1)
+        return -errno;
+    return len;
+}
+
 static size_t handle_aiocb_rw_linear(struct qemu_paiocb *aiocb, char *buf)
 {
     size_t offset = 0;
@@ -140,12 +199,34 @@ static size_t handle_aiocb_rw(struct qemu_paiocb *aiocb)
     size_t nbytes;
     char *buf;
 
-    if (!aiocb_needs_copy(aiocb) && aiocb->aio_niov == 1) {
+    if (!aiocb_needs_copy(aiocb)) {
         /*
          * If there is just a single buffer, and it is properly aligned
          * we can just use plain pread/pwrite without any problems.
          */
-        return handle_aiocb_rw_linear(aiocb, aiocb->aio_iov->iov_base);
+        if (aiocb->aio_niov == 1)
+             return handle_aiocb_rw_linear(aiocb, aiocb->aio_iov->iov_base);
+
+        /*
+         * We have more than one iovec, and all are properly aligned.
+         *
+         * Try preadv/pwritev first and fall back to linearizing the
+         * buffer if it's not supported.
+         */
+       if (preadv_present) {
+            nbytes = handle_aiocb_rw_vector(aiocb);
+            if (nbytes == aiocb->aio_nbytes)
+               return nbytes;
+            if (nbytes < 0 && nbytes != -ENOSYS)
+                return nbytes;
+            preadv_present = 0;
+        }
+
+        /*
+         * XXX(hch): short read/write.  no easy way to handle the reminder
+         * using these interfaces.  For now retry using plain
+         * pread/pwrite?
+         */
     }
 
     /*