Hi Akira,
That's the major point. Fair enough :-)
Thanks,
--Jason
On Tue, May 9, 2017 at 10:56 PM, Akira Yokosawa <akiyks@xxxxxxxxx> wrote:
> On 2017/05/09 16:48:12 +0800, Junchang Wang wrote:
>> Oops. Forgot the summary in previous email. Resend the patch.
>>
>>
>> The Answer to Quick Quiz 5.27 is a bit hard to follow. Rewrite it.
>>
>> Signed-off-by: Junchang Wang <junchangwang@xxxxxxxxx>
>> ---
>> count/count.tex | 14 +++++++-------
>> 1 file changed, 7 insertions(+), 7 deletions(-)
>>
>> diff --git a/count/count.tex b/count/count.tex
>> index cc47554..6dfc7a6 100644
>> --- a/count/count.tex
>> +++ b/count/count.tex
>> @@ -1258,13 +1258,13 @@ machine.
>> fast and scalable while allowing readers to also enjoy
>> reasonable performance and scalability?
>> \QuickQuizAnswer{
>> - One approach would be to maintain a global approximation
>> - to the value.
>> - Readers would increment their per-thread variable, but when it
>> - reached some predefined limit, atomically add it to a global
>> - variable, then zero their per-thread variable.
>> - This would permit a tradeoff between average increment overhead
>> - and accuracy of the value read out.
>> + One approach would be to add a global variable maintaining a
>> + approximation to the exact value. An updater would increment its
>> + per-thread variable, and when its value reaches predefined limit,
>> + atomically add the value to the global variable, then zero its
>> + per-thread variable. Readers simply return the value of global variable,
>> + enjoying reasonable performance. This would permit a tradeoff between
>> + average increment overhead and accuracy of the value read out.
>>
>> The reader is encouraged to think up and try out other approaches,
>> for example, using a combining tree.
>>
>
> Hi Junchang,
>
> What confused you seems to be a simple typo.
> Isn't the following one-liner sufficient for you?
>
> Thanks, Akira
>
> --8<---->8--
> From 725b32938e0cbc245e5a528fd475951bb8be1de5 Mon Sep 17 00:00:00 2001
> From: Akira Yokosawa <akiyks@xxxxxxxxx>
> Date: Tue, 9 May 2017 23:39:57 +0900
> Subject: [PATCH] count: Fix typo in Answer to Quick Quiz 5.27
>
> Reported-by: Junchang Wang <junchangwang@xxxxxxxxx>
> Signed-off-by: Akira Yokosawa <akiyks@xxxxxxxxx>
> ---
> count/count.tex | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/count/count.tex b/count/count.tex
> index cc47554..096b53d 100644
> --- a/count/count.tex
> +++ b/count/count.tex
> @@ -1260,7 +1260,7 @@ machine.
> \QuickQuizAnswer{
> One approach would be to maintain a global approximation
> to the value.
> - Readers would increment their per-thread variable, but when it
> + Updaters would increment their per-thread variable, but when it
> reached some predefined limit, atomically add it to a global
> variable, then zero their per-thread variable.
> This would permit a tradeoff between average increment overhead
> --
> 2.7.4
>
>
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