qemu-devel
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] [PATCH] ui/cocoa.m: add Speed menu


From: Eric Blake
Subject: Re: [Qemu-devel] [PATCH] ui/cocoa.m: add Speed menu
Date: Thu, 29 Dec 2016 11:35:23 -0600
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1

On 12/29/2016 11:24 AM, Programmingkid wrote:
> Programs running inside of QEMU can sometimes use more CPU time than is really
> needed. To solve this problem, we just need to throttle the virtual CPU. This
> feature will stop laptops from burning up. 
> 
> This patch adds a menu called Speed that has menu items from 10 to 1. They
> represent the speed options. 10 is full speed and 1 is slowest.

Why not make it a type-in box where the user specifies a percentage, up
to 100 (unthrottled)?

Is this feature present in the other GUIs, such as the gtk view?  I'm
reluctant to invent features for the less-tested cocoa interface that
are not FIRST present on other interfaces.

> 
> Signed-off-by: John Arbuckle <address@hidden>
> ---
>  ui/cocoa.m | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 56 insertions(+)

>  
> +/* Used by the Speed menu items */
> +- (void)adjustSpeed:(id)sender
> +{
> +    /* 10 has two digits in it - plus the NULL termination at the end */
> +    const int max_title_size = 3;
> +    char menu_item_title[max_title_size];
> +    int speed, menu_number, count, item;
> +    NSMenu *menu;
> +    NSArray *itemArray;
> +
> +    // uncheck all the menu items in the Speed menu
> +    menu = [sender menu];
> +     if(menu != nil)
> +     {
> +             count = [[menu itemArray] count];

TAB damage.

> +             itemArray = [menu itemArray];
> +             for(item = 0; item < count; item++)  // unselect each item

Space after 'for'.

> +                     [[itemArray objectAtIndex: item] setState: NSOffState];
> +     }
> +
> +    // check the menu item
> +    [sender setState: NSOnState];
> +
> +    // get the menu number
> +    snprintf(menu_item_title, max_title_size, "%s", [[sender title] 
> cStringUsingEncoding: NSASCIIStringEncoding]);
> +    sscanf(menu_item_title, "%d", &menu_number);

Eew. That just feels fragile.

> +
> +     /* Calculate the speed */
> +    // inverse relationship between menu item number and speed
> +    speed = -1 * menu_number + 10;
> +    speed = speed * 10;
> +    cpu_throttle_set(speed);
> +    COCOA_DEBUG("cpu throttling at %d%c\n", cpu_throttle_get_percentage(), 
> '%');

Again, I think that '100%' makes more intuitive sense than '10' for
knowing that my VM is running unthrottled.  The amount of math you have
to do to transform the menu numbers into the cpu_throttle_set() call is
a sign that your mapping is rather complex compared to a more intuitive
setup.

> +}
> +
>  @end
>  
>  
> @@ -1316,6 +1353,25 @@ int main (int argc, const char * argv[]) {
>      [menuItem setSubmenu:menu];
>      [[NSApp mainMenu] addItem:menuItem];
>  
> +    // Speed menu
> +    menu = [[NSMenu alloc] initWithTitle:@"Speed"];
> +    menuItem = [[[NSMenuItem alloc] initWithTitle:@"10 (fastest)" 
> action:@selector(adjustSpeed:) keyEquivalent:@""] autorelease];
> +    [menuItem setState: NSOnState];
> +    [menu addItem: menuItem];
> +    [menu addItem: [[[NSMenuItem alloc] initWithTitle:@"9" 
> action:@selector(adjustSpeed:) keyEquivalent:@""] autorelease]];
> +    [menu addItem: [[[NSMenuItem alloc] initWithTitle:@"8" 
> action:@selector(adjustSpeed:) keyEquivalent:@""] autorelease]];

And this adds a LOT of menu items, compared to what you could get if a
single menu item opens up a dialog box for typing in a number that is
validated to be between 1 and 100.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

Attachment: signature.asc
Description: OpenPGP digital signature


reply via email to

[Prev in Thread] Current Thread [Next in Thread]