WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

Re: [Xen-devel] [RFC][PATCH] 2/3] [TOOLS][XENTRACE] Update tools to writ

To: "Tony Breeds" <tony@xxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [RFC][PATCH] 2/3] [TOOLS][XENTRACE] Update tools to write data to disk in a known endian'ness.
From: "George Dunlap " <dunlapg@xxxxxxxxx>
Date: Thu, 30 Nov 2006 11:27:27 -0500
Cc: Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
Delivery-date: Thu, 30 Nov 2006 08:27:32 -0800
Domainkey-signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:sender:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references:x-google-sender-auth; b=pZYE6ugEUH0b+9wyLz4yHtX0OHSP1+rL13sz1nuKSFFmMBHg7yC5qPF0etYY/Bp5rRwAFnc6v4vGOzCjvK9NJ0tSRQNFF3916VoAxufpET3hQ3U0UDbKJPYM4gKFvU96Mh9soDfS4J735jaEKxuq+JPDTBgrYf8fNTK2a+ltnkg=
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
In-reply-to: <200611300601.kAU614gE025340@xxxxxxxxxxxxxxxxxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <1164866397.55184.656346817748.qpush@thor> <200611300601.kAU614gE025340@xxxxxxxxxxxxxxxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Do you have an idea how much extra cpu this takes for high-bandwidth tracing?

I'm using xentrace for performance analysis, and it's already got a
measurable impact due to the disk bandwidth and copying.  I'd like to
keep that as minimal as possible.

-George

On 11/30/06, Tony Breeds <tony@xxxxxxxxxxxxxxxxxx> wrote:
Use network byte order when writing data to disk, making the data portable to
any machine.

Signed-off-by: Tony Breeds <tony@xxxxxxxxxxxxxxxxxx>
---

 tools/xentrace/xentrace.c      |   47 ++++++++++++++++++++++++++++++++++-------
 tools/xentrace/xentrace_format |    7 +++---
 2 files changed, 44 insertions(+), 10 deletions(-)

Index: xen-unstable.hg-mainline.xentrace/tools/xentrace/xentrace.c
===================================================================
--- xen-unstable.hg-mainline.xentrace.orig/tools/xentrace/xentrace.c
+++ xen-unstable.hg-mainline.xentrace/tools/xentrace/xentrace.c
@@ -28,6 +28,20 @@

 #include <xenctrl.h>

+#include <arpa/inet.h> /* hton*(), ntoh*() */
+#include <endian.h>
+
+/* There is no 64-bit htonll, so create one */
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+#define        htonll(x)   ( (((uint64_t)htonl(x)) << 32) + htonl(x >> 32) )
+#define        ntohll(x)   ( (((uint64_t)ntohl(x)) << 32) + ntohl(x >> 32) )
+#else
+#define        htonll(x)   (x)
+#define        ntohll(x)   (x)
+#endif
+
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
+
 #define PERROR(_m, _a...)                                       \
 do {                                                            \
     int __saved_errno = errno;                                  \
@@ -90,12 +104,30 @@ struct timespec millis_to_timespec(unsig
  * Outputs the trace record to a filestream, prepending the CPU ID of the
  * source trace buffer.
  */
-void write_rec(unsigned int cpu, struct t_rec *rec, FILE *out)
+void write_rec(uint32_t cpu, struct t_rec *rec, FILE *out)
 {
     size_t written = 0;
-    written += fwrite(&cpu, sizeof(cpu), 1, out);
-    written += fwrite(rec, sizeof(*rec), 1, out);
-    if ( written != 2 )
+    int i;
+    /* Place network byte order representation in temp vars, rather than
+     * write back into kernel/xen memory */
+    uint64_t tmp64;
+    uint32_t tmp32;
+
+    tmp32 = htonl(cpu);
+    written += fwrite(&tmp32, sizeof(tmp32), 1, out);
+
+    tmp64 = htonll(rec->cycles);
+    written += fwrite(&tmp64, sizeof(tmp64), 1, out);
+
+    tmp32 = htonl(rec->event);
+    written += fwrite(&tmp32, sizeof(tmp32), 1, out);
+
+    for ( i=0; i<ARRAY_SIZE(rec->data); i++ ) {
+        tmp64 = htonl(rec->data[i]);
+        written += fwrite(&tmp64, sizeof(tmp64), 1, out);
+    }
+
+    if ( written != 8 )
     {
         PERROR("Failed to write trace record");
         exit(EXIT_FAILURE);
@@ -147,6 +179,7 @@ struct t_buf *map_tbufs(unsigned long tb
         exit(EXIT_FAILURE);
     }

+    /* On PPC (At least) the DOMID arg is ignored in dom0 */
     tbufs_mapped = xc_map_foreign_range(xc_handle, DOMID_XEN,
                                         size * num, PROT_READ | PROT_WRITE,
                                         tbufs_mfn);
@@ -253,7 +286,7 @@ struct t_rec **init_rec_ptrs(struct t_bu
 /**
  * get_num_cpus - get the number of logical CPUs
  */
-unsigned int get_num_cpus(void)
+uint32_t get_num_cpus(void)
 {
     xc_physinfo_t physinfo;
     int xc_handle = xc_interface_open();
@@ -282,14 +315,14 @@ unsigned int get_num_cpus(void)
  */
 int monitor_tbufs(FILE *logfile)
 {
-    int i;
+    uint32_t i;

     void *tbufs_mapped;          /* pointer to where the tbufs are mapped    */
     struct t_buf **meta;         /* pointers to the trace buffer metadata    */
     struct t_rec **data;         /* pointers to the trace buffer data areas
                                   * where they are mapped into user space.   */
     unsigned long tbufs_mfn;     /* mfn of the tbufs                         */
-    unsigned int  num;           /* number of trace buffers / logical CPUS   */
+    uint32_t num;                /* number of trace buffers / logical CPUS   */
     unsigned long size;          /* size of a single trace buffer            */

     int size_in_recs;
Index: xen-unstable.hg-mainline.xentrace/tools/xentrace/xentrace_format
===================================================================
--- xen-unstable.hg-mainline.xentrace.orig/tools/xentrace/xentrace_format
+++ xen-unstable.hg-mainline.xentrace/tools/xentrace/xentrace_format
@@ -84,10 +84,11 @@ interrupted = 0
 defs = read_defs(arg[0])

 # structure of trace record + prepended CPU id (as output by xentrace):
-# CPU(I) TSC(Q) EVENT(L) D1(L) D2(L) D3(L) D4(L) D5(L)
+# CPU(L) TSC(Q) EVENT(L) D1(Q) D2(Q) D3(Q) D4(Q) D5(Q)
 # read CPU id separately to avoid structure packing problems on 64-bit arch.
-CPUREC = "I"
-TRCREC = "QLLLLLL"
+# Force network byte order.
+CPUREC = "!L"
+TRCREC = "!QLQQQQQ"

 last_tsc = [0]



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel

<Prev in Thread] Current Thread [Next in Thread>