migration:

* add avx2 instruction optimization, speeds up zero-page checking on compatible architectures and compilers (gcc 4.9+) * add additional postcopy stats to 'info migrate' output -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAABAgAGBQJW3resAAoJEB6aO1+FQIO2DDAQAJOooSKFVH0BmnUanpDu7sw9 8xMPRSXCVN6IiK1cmL8Gm3vD20vyg0GwE6V5P8VBVZWedKpnSMgVNLDs/D8PH0zq oGqc+kLKJJkUePRZ5AxTZe2BPzjsd+TB17TdqML21854X5ysJRNA3RTGjntvSQtD ANFVwrZWmh8Br7+4rtJAoyF5GCta8ti8ctOnAUoKpxpn0NsjC8CgkP03AIXJcart fZ5gDAzZkXtgxhu/Dws1oIaVbXbMrdYWata3ruMX9OCmPe+DaU75l8Q/t7q2iVPj 5VFvFSDu7czxIGWpWPqZC5SYEPyupOcixWlR770U9OpYKlrQMLO1CEAHm4VIBIK8 cKIPnuQgAATj6eQ1oE6k0vvSHgzXhFOw7nvSkI3bS6JPq2KY1lx8mAYAUSZtM8/w DJ6zFw/VDKY0eFc42u1/ja6Ojv3oe5YbbRdc5L9reHWC4Fnt5/yLVmr6PNj8nROM AjyyjZ5+RuFljIzvsrFYdx+0673mmSLMzGPDQsfFcddIcxX87aoVG6FS+JC4wCQ+ iS52J/vyKGeVTucIklfigRFiSBFEHbyzX5uO62zA/zzl1CTkfZ3AaRjekz0Vr+Wu cNIkA506+MC4E30LGsrm2zBLO5Nt1uco6pNSdLQsw4UZjkE+ZJ9VhSTgHR5FIMll 1PBs0B+tSUJMaqXfpWDs =7PTp -----END PGP SIGNATURE----- Merge remote-tracking branch 'remotes/amit-migration/tags/migration-for-2.6-6' into staging migration: * add avx2 instruction optimization, speeds up zero-page checking on compatible architectures and compilers (gcc 4.9+) * add additional postcopy stats to 'info migrate' output # gpg: Signature made Tue 08 Mar 2016 11:29:48 GMT using RSA key ID 854083B6 # gpg: Good signature from "Amit Shah <amit@amitshah.net>" # gpg: aka "Amit Shah <amit@kernel.org>" # gpg: aka "Amit Shah <amitshah@gmx.net>" * remotes/amit-migration/tags/migration-for-2.6-6: cutils: add avx2 instruction optimization configure: detect ifunc and avx2 attribute Postcopy: Fix sync count in info migrate Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2016-03-09 01:07:16 +00:00 · 2016-03-09 01:07:16 +00:00 · 8519c8e073
parent 3293680dc7 28b90d9c19
commit 8519c8e073
4 changed files with 143 additions and 11 deletions
--- a/21
+++ b/21
@ -280,6 +280,7 @@ libusb=""
 usb_redir=""
 opengl=""
 opengl_dmabuf="no"
+avx2_opt="no"
 zlib="yes"
 lzo=""
 snappy=""
@ -1773,6 +1774,21 @@ EOF
 fi

 ##########################################
+# avx2 optimization requirement check
+
+cat > $TMPC << EOF
+static void bar(void) {}
+static void *bar_ifunc(void) {return (void*) bar;}
+static void foo(void) __attribute__((ifunc("bar_ifunc")));
+int main(void) { foo(); return 0; }
+EOF
+if compile_prog "-mavx2" "" ; then
+    if readelf --syms $TMPE |grep "IFUNC.*foo" >/dev/null 2>&1; then
+        avx2_opt="yes"
+    fi
+fi
+
+#########################################
 # zlib check

 if test "$zlib" != "no" ; then
@ -4790,6 +4806,7 @@ echo "bzip2 support     $bzip2"
 echo "NUMA host support $numa"
 echo "tcmalloc support  $tcmalloc"
 echo "jemalloc support  $jemalloc"
+echo "avx2 optimization $avx2_opt"

 if test "$sdl_too_old" = "yes"; then
 echo "-> Your SDL version is too old - please upgrade to have SDL support"
@ -5178,6 +5195,10 @@ if test "$opengl" = "yes" ; then
  fi
 fi

+if test "$avx2_opt" = "yes" ; then
+  echo "CONFIG_AVX2_OPT=y" >> $config_host_mak
+fi
+
 if test "$lzo" = "yes" ; then
  echo "CONFIG_LZO=y" >> $config_host_mak
 fi
--- a/include/qemu-common.h
+++ b/include/qemu-common.h
@ -476,13 +476,7 @@ void qemu_hexdump(const char *buf, FILE *fp, const char *prefix, size_t size);
 #endif

 #define BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR 8
-static inline bool
-can_use_buffer_find_nonzero_offset(const void *buf, size_t len)
-{
-    return (len % (BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR
-                   * sizeof(VECTYPE)) == 0
-            && ((uintptr_t) buf) % sizeof(VECTYPE) == 0);
-}
+bool can_use_buffer_find_nonzero_offset(const void *buf, size_t len);
 size_t buffer_find_nonzero_offset(const void *buf, size_t len);

 /*
--- a/migration/migration.c
+++ b/migration/migration.c
@ -635,6 +635,7 @@ MigrationInfo *qmp_query_migrate(Error **errp)
        info->ram->normal_bytes = norm_mig_bytes_transferred();
        info->ram->dirty_pages_rate = s->dirty_pages_rate;
        info->ram->mbps = s->mbps;
+        info->ram->dirty_sync_count = s->dirty_sync_count;

        if (blk_mig_active()) {
            info->has_disk = true;
--- a/util/cutils.c
+++ b/util/cutils.c
@ -160,6 +160,14 @@ int qemu_fdatasync(int fd)
 #endif
 }

+static bool
+can_use_buffer_find_nonzero_offset_inner(const void *buf, size_t len)
+{
+    return (len % (BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR
+                   * sizeof(VECTYPE)) == 0
+            && ((uintptr_t) buf) % sizeof(VECTYPE) == 0);
+}
+
 /*
 * Searches for an area with non-zero content in a buffer
 *
@ -168,8 +176,8 @@ int qemu_fdatasync(int fd)
 * and addr must be a multiple of sizeof(VECTYPE) due to
 * restriction of optimizations in this function.
 *
- * can_use_buffer_find_nonzero_offset() can be used to check
- * these requirements.
+ * can_use_buffer_find_nonzero_offset_inner() can be used to
+ * check these requirements.
 *
 * The return value is the offset of the non-zero area rounded
 * down to a multiple of sizeof(VECTYPE) for the first
@ -180,13 +188,13 @@ int qemu_fdatasync(int fd)
 * If the buffer is all zero the return value is equal to len.
 */

-size_t buffer_find_nonzero_offset(const void *buf, size_t len)
+static size_t buffer_find_nonzero_offset_inner(const void *buf, size_t len)
 {
    const VECTYPE *p = buf;
    const VECTYPE zero = (VECTYPE){0};
    size_t i;

-    assert(can_use_buffer_find_nonzero_offset(buf, len));
+    assert(can_use_buffer_find_nonzero_offset_inner(buf, len));

    if (!len) {
        return 0;
@ -215,6 +223,114 @@ size_t buffer_find_nonzero_offset(const void *buf, size_t len)
    return i * sizeof(VECTYPE);
 }

+/*
+ * GCC before version 4.9 has a bug which will cause the target
+ * attribute work incorrectly and failed to compile in some case,
+ * restrict the gcc version to 4.9+ to prevent the failure.
+ */
+
+#if defined CONFIG_AVX2_OPT && QEMU_GNUC_PREREQ(4, 9)
+#pragma GCC push_options
+#pragma GCC target("avx2")
+#include <cpuid.h>
+#include <immintrin.h>
+
+#define AVX2_VECTYPE        __m256i
+#define AVX2_SPLAT(p)       _mm256_set1_epi8(*(p))
+#define AVX2_ALL_EQ(v1, v2) \
+    (_mm256_movemask_epi8(_mm256_cmpeq_epi8(v1, v2)) == 0xFFFFFFFF)
+#define AVX2_VEC_OR(v1, v2) (_mm256_or_si256(v1, v2))
+
+static bool
+can_use_buffer_find_nonzero_offset_avx2(const void *buf, size_t len)
+{
+    return (len % (BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR
+                   * sizeof(AVX2_VECTYPE)) == 0
+            && ((uintptr_t) buf) % sizeof(AVX2_VECTYPE) == 0);
+}
+
+static size_t buffer_find_nonzero_offset_avx2(const void *buf, size_t len)
+{
+    const AVX2_VECTYPE *p = buf;
+    const AVX2_VECTYPE zero = (AVX2_VECTYPE){0};
+    size_t i;
+
+    assert(can_use_buffer_find_nonzero_offset_avx2(buf, len));
+
+    if (!len) {
+        return 0;
+    }
+
+    for (i = 0; i < BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR; i++) {
+        if (!AVX2_ALL_EQ(p[i], zero)) {
+            return i * sizeof(AVX2_VECTYPE);
+        }
+    }
+
+    for (i = BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR;
+         i < len / sizeof(AVX2_VECTYPE);
+         i += BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR) {
+        AVX2_VECTYPE tmp0 = AVX2_VEC_OR(p[i + 0], p[i + 1]);
+        AVX2_VECTYPE tmp1 = AVX2_VEC_OR(p[i + 2], p[i + 3]);
+        AVX2_VECTYPE tmp2 = AVX2_VEC_OR(p[i + 4], p[i + 5]);
+        AVX2_VECTYPE tmp3 = AVX2_VEC_OR(p[i + 6], p[i + 7]);
+        AVX2_VECTYPE tmp01 = AVX2_VEC_OR(tmp0, tmp1);
+        AVX2_VECTYPE tmp23 = AVX2_VEC_OR(tmp2, tmp3);
+        if (!AVX2_ALL_EQ(AVX2_VEC_OR(tmp01, tmp23), zero)) {
+            break;
+        }
+    }
+
+    return i * sizeof(AVX2_VECTYPE);
+}
+
+static bool avx2_support(void)
+{
+    int a, b, c, d;
+
+    if (__get_cpuid_max(0, NULL) < 7) {
+        return false;
+    }
+
+    __cpuid_count(7, 0, a, b, c, d);
+
+    return b & bit_AVX2;
+}
+
+bool can_use_buffer_find_nonzero_offset(const void *buf, size_t len) \
+         __attribute__ ((ifunc("can_use_buffer_find_nonzero_offset_ifunc")));
+size_t buffer_find_nonzero_offset(const void *buf, size_t len) \
+         __attribute__ ((ifunc("buffer_find_nonzero_offset_ifunc")));
+
+static void *buffer_find_nonzero_offset_ifunc(void)
+{
+    typeof(buffer_find_nonzero_offset) *func = (avx2_support()) ?
+        buffer_find_nonzero_offset_avx2 : buffer_find_nonzero_offset_inner;
+
+    return func;
+}
+
+static void *can_use_buffer_find_nonzero_offset_ifunc(void)
+{
+    typeof(can_use_buffer_find_nonzero_offset) *func = (avx2_support()) ?
+        can_use_buffer_find_nonzero_offset_avx2 :
+        can_use_buffer_find_nonzero_offset_inner;
+
+    return func;
+}
+#pragma GCC pop_options
+#else
+bool can_use_buffer_find_nonzero_offset(const void *buf, size_t len)
+{
+    return can_use_buffer_find_nonzero_offset_inner(buf, len);
+}
+
+size_t buffer_find_nonzero_offset(const void *buf, size_t len)
+{
+    return buffer_find_nonzero_offset_inner(buf, len);
+}
+#endif
+
 /*
 * Checks if a buffer is all zeroes
 *