From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=32830 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PmwJU-0000Zp-9g for qemu-devel@nongnu.org; Tue, 08 Feb 2011 17:45:37 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1PmwJS-0001bX-Qe for qemu-devel@nongnu.org; Tue, 08 Feb 2011 17:45:36 -0500 Received: from mail-gy0-f173.google.com ([209.85.160.173]:57554) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1PmwJS-0001bL-O8 for qemu-devel@nongnu.org; Tue, 08 Feb 2011 17:45:34 -0500 Received: by gye5 with SMTP id 5so2806146gye.4 for ; Tue, 08 Feb 2011 14:45:33 -0800 (PST) Received: from [136.162.34.1] ([136.162.34.1]) by shadowfax.no-ip.com for qemu-devel@nongnu.org; Tue, 8 Feb 2011 16:45:28 -0600 From: "Adnan Khaleel" Message-ID: <20110208224528.06470d27@shadowfax.no-ip.com> Date: Tue, 08 Feb 2011 16:45:28 -0600 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------bcf60e0a234a961899e319d4b93a44ef" Subject: [Qemu-devel] Guest bootup time varies with simulated memory size Reply-To: adnan@khaleel.us List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org This is a multi-part message in MIME format. -------------bcf60e0a234a961899e319d4b93a44ef Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable In trying out various simulated memory sized in Qemu, there is a noticea= ble increase in guest bootup times with more memory. My metric of measur= ing how long linux takes to boot is probably not the most consistent but= here is what I've observed. In Qemu 0.12.5 512m ~ 4 mins 2048m ~ 7 mins In the latest version of Qemu 0.14.0-rc0, things have improved 512m ~ 3 mins 30 secs 2048m ~ 4 mins 45 secs As you can see, boot up time increases with more memory. My host system = itself has 16G of memory so swapping is not the issue.=20 Its quite likely that the guest linux kernel maybe doing something with = this extra memory but I haven't looked into possible causes. I just want= ed to see if the developers would know of an explanation as to whats hap= pening as it would seem that adding more memory to the guest should impr= ove performance.=20 I will run some measurements after boot to see if there is any variation= in overall simulation speed or if its just restricted to bootup. - AK=20 -------------bcf60e0a234a961899e319d4b93a44ef Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable In trying out various simulated memory sized in Qemu, there is a noticea= ble increase in guest bootup times with more memory. My metric of measur= ing how long linux takes to boot is probably not the most consistent but= here is what I've observed.

In Qemu 0.12.5

512m ~ 4 mins

2048m ~ 7 mins

In the latest version of Qemu 0.14.0-rc0, things have improved

512m ~ 3 mins 30 secs

2048m ~ 4 mins 4= 5 secs

As you can see, boot up time increases w= ith more memory. My host system itself has 16G of memory so swapping is = not the issue.

Its quite likely that the guest linux ker= nel maybe doing something with this extra memory but I haven't looked in= to possible causes. I just wanted to see if the developers would know of= an explanation as to whats happening as it would seem that adding = more memory to the guest should improve performance.

I will run some measurements after boot to see if there is a= ny variation in overall simulation speed or if its just restricted to bo= otup.

- AK

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