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

[Xen-devel] [PATCH] xen: Avoid useless allocation in Xen case.

To: QEMU-devel <qemu-devel@xxxxxxxxxx>
Subject: [Xen-devel] [PATCH] xen: Avoid useless allocation in Xen case.
From: Anthony PERARD <anthony.perard@xxxxxxxxxx>
Date: Mon, 1 Aug 2011 20:26:21 +0100
Cc: Anthony PERARD <anthony.perard@xxxxxxxxxx>, Xen Devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Alexander Graf <agraf@xxxxxxx>, Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Delivery-date: Mon, 01 Aug 2011 12:28:27 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
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/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
The code_gen_buffer is not use by Xen and can be really big (several
GB). Even if the host RAM is not used, this buffer just burn the address
space of the QEMU process.

So to "avoid" this allocation, the asked tb_size is set to the minimum.

The other way to do that would be to not call code_gen_alloc when Xen is
enabled.

Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
---
 vl.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/vl.c b/vl.c
index d8c7c01..bd60a89 100644
--- a/vl.c
+++ b/vl.c
@@ -3106,6 +3106,14 @@ int main(int argc, char **argv, char **envp)
         }
     }
 
+    if (xen_enabled()) {
+        /* Allocate only the minimum amount of memory for the code_gen_buffer.
+         * Xen does not use it and we need the virtual address space for the
+         * MapCache.
+         */
+        tb_size = 1;
+    }
+
     /* init the dynamic translator */
     cpu_exec_init_all(tb_size * 1024 * 1024);
 
-- 
Anthony PERARD


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