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Re: [Qemu-devel] [PATCH] upgrading emulated UART to 16550A
From: |
Stefano Stabellini |
Subject: |
Re: [Qemu-devel] [PATCH] upgrading emulated UART to 16550A |
Date: |
Tue, 05 Aug 2008 15:17:46 +0100 |
User-agent: |
Thunderbird 2.0.0.14 (X11/20080505) |
Thiemo Seufer wrote:
>> +/* Rate limit serial requests so that e.g. grub on a serial console
>> + doesn't kill dom0. Simple token bucket. If we get some actual
>> + data from the user, instantly refil the bucket. */
>> +
>> +/* How long it takes to generate a token, in nanoseconds. */
>> +#define TOKEN_PERIOD 1000000
>> +/* Maximum and initial size of token bucket */
>> +#define TOKENS_MAX 100000
>
> This token business probably needs a bit more explanation, at a glance
> I didn't figure out what it is meant to do (and why the constants above
> are good).
>
The token bucket was introduced to rate limit serial requests, mainly
for performance reasons (grub makes too many requests).
However I realize that conceptually it doesn't belong to qemu, so I am
going to send another patch soon without the token bucket.