Daniel Lemire's blog
A performance trap: when store forwarding fails
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A performance trap: when store forwarding fails
source
Daniel Lemire's blog
A performance trap: when store forwarding fails
A store does not go straight into the cache. Waiting for that write would stall the processor. It sits in a store buffer, and a later load can take its bytes from that buffer. That is store forwarding. Forwarding works when the load is the same size as the…
政府网站也开始用AI重构了
https://sbj.cnipa.gov.cn/
https://sbj.cnipa.gov.cn/
杰哥的{教学，运维，编程，调板子}小笔记
用 XRDP + X11 转发实现带音频的图形界面转发
背景
最近遇到一个需求，在机器 A 上跑一个图形界面程序，但因为是远程访问，所以传统的办法就是开个 X11 Forwarding，或者跑个 VNC/RDP Server。但我有音频转发的需求，本地是 macOS，又不好在机器 A 上装 XRDP+桌面环境，于是在机器 B 上跑 XRDP Server，在机器 A 上通过 X11 Forwarding + Unix Socket Forwarding 实现图形界面和音频在机器 B 上的播放，再通过 RDP 客户端在 macOS 上实现带音频的图形界面浏览。
具体实现方法
具体实现方法不难，主要是在机器 B 上做一些配置：
1. 安装 XRDP，配置桌面环境，我用的是 Xfce4
2. 安装 pipewire-module-xrdp，关闭 pulseaudio 服务，改为 pipewire + pipewire-pulse + wireplumber
3. 带 X11 Forwarding 连接到机器 A，同时通过 Unix Socket 转发 pulseaudio 的 Unix Socket：
然后在 SSH Session 里跑带图形界面的程序即可，它就会通过 ssh 转发的 X11 在 XRDP 的 DISPLAY 上显示，再通过 pulse/native 的 Unix Socket 播放音频。
最后，通过 RDP Client（Windows App）连接到机器 B，就可以在看到图形界面的同时，也有正确的音频了。
source
用 XRDP + X11 转发实现带音频的图形界面转发
背景
最近遇到一个需求，在机器 A 上跑一个图形界面程序，但因为是远程访问，所以传统的办法就是开个 X11 Forwarding，或者跑个 VNC/RDP Server。但我有音频转发的需求，本地是 macOS，又不好在机器 A 上装 XRDP+桌面环境，于是在机器 B 上跑 XRDP Server，在机器 A 上通过 X11 Forwarding + Unix Socket Forwarding 实现图形界面和音频在机器 B 上的播放，再通过 RDP 客户端在 macOS 上实现带音频的图形界面浏览。
具体实现方法
具体实现方法不难，主要是在机器 B 上做一些配置：
1. 安装 XRDP，配置桌面环境，我用的是 Xfce4
2. 安装 pipewire-module-xrdp，关闭 pulseaudio 服务，改为 pipewire + pipewire-pulse + wireplumber
3. 带 X11 Forwarding 连接到机器 A，同时通过 Unix Socket 转发 pulseaudio 的 Unix Socket：
DISPLAY=XRDP_DESKTOP_HERE ssh -X -Y -R /run/user/UID_A_HERE/pulse/native:/run/user/UID_B_HERE/pulse/native host_a然后在 SSH Session 里跑带图形界面的程序即可，它就会通过 ssh 转发的 X11 在 XRDP 的 DISPLAY 上显示，再通过 pulse/native 的 Unix Socket 播放音频。
最后，通过 RDP Client（Windows App）连接到机器 B，就可以在看到图形界面的同时，也有正确的音频了。
source
Daniel Lemire's blog
In C++, = default and {} are not the same constructor
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In C++, = default and {} are not the same constructor
source
Daniel Lemire's blog
In C++, = default and {} are not the same constructor
You can write an empty default constructor as span() = default or as span() {}. It can have remarkable effects on performance. struct span { const char *p; int len; const char *end; span() = default; // or span() {} span(const char *s, int n) : p(s), len(n)…
Daniel Lemire's blog
Beating the compiler at signed 32-bit division
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Beating the compiler at signed 32-bit division
source
Daniel Lemire's blog
Beating the compiler at signed 32-bit division
Dividing integers is slow on our processors. A 32-bit division costs: processor latency throughput Emerald Rapids about 12 cycles one every 6 cycles Zen 4 9 to 12 cycles one every 6 cycles Zen 5 10 to 13 cycles one every 6 cycles Arrow Lake performance core…
2026年CoLT也是标配了
CoLT: Coalesced Large-Reach TLBs, MICRO 2012
CoLT: Coalesced Large-Reach TLBs, MICRO 2012
极客湾也是用上topdown了
Chips and Cheese
“Performance” Oryon: Qualcomm’s Little Core
#ChipAndCheese
Telegraph | source
(author: Chester Lam)
“Performance” Oryon: Qualcomm’s Little Core
#ChipAndCheese
Telegraph | source
(author: Chester Lam)
Arch Linux: Recent news updates
Update to php ≥ 8.5.12 and/or php-legacy ≥ 8.3.36 to prevent remote code execution
PHP versions prior to 8.5.12 and 8.3.36 are affected by CVE-2026-109618 and CVE-2026-109619, which allow for remote code execution.
For any system publicly exposing a PHP application with the help of a prior version of PHP, we urge users to upgrade those systems to the latest available version of PHP (php ≥ 8.5.12 and php-legacy ≥ 8.3.36) immediately.
source
(author: David Runge)
Update to php ≥ 8.5.12 and/or php-legacy ≥ 8.3.36 to prevent remote code execution
PHP versions prior to 8.5.12 and 8.3.36 are affected by CVE-2026-109618 and CVE-2026-109619, which allow for remote code execution.
For any system publicly exposing a PHP application with the help of a prior version of PHP, we urge users to upgrade those systems to the latest available version of PHP (php ≥ 8.5.12 and php-legacy ≥ 8.3.36) immediately.
source
(author: David Runge)
Arch Linux: Recent news updates
Update to ca-certificates-mozilla ≥ 3.131.1-1 to prevent man-in-the-middle attacks
On 2026-10-20 it was revealed, that several certificates of the eMudhra intermediate Certificate Authority have been compromised.
The compromised certificates have been removed/invalidated with ca-certificates-mozilla ≥ 3.131.1-1.
Without an update to this central certificate bundle, systems are susceptible to man-in-the-middle attacks. As such, we urge everyone to upgrade their systems immediately.
source
(author: David Runge)
Update to ca-certificates-mozilla ≥ 3.131.1-1 to prevent man-in-the-middle attacks
On 2026-10-20 it was revealed, that several certificates of the eMudhra intermediate Certificate Authority have been compromised.
The compromised certificates have been removed/invalidated with ca-certificates-mozilla ≥ 3.131.1-1.
Without an update to this central certificate bundle, systems are susceptible to man-in-the-middle attacks. As such, we urge everyone to upgrade their systems immediately.
source
(author: David Runge)
Chips and Cheese
Nvidia Vera’s System Architecture: Pushing Bandwidth
#ChipAndCheese
Telegraph | source
(author: Chester Lam)
Nvidia Vera’s System Architecture: Pushing Bandwidth
#ChipAndCheese
Telegraph | source
(author: Chester Lam)
Daniel Lemire's blog
Decoding base64 in Python at 10 gigabytes per second
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Decoding base64 in Python at 10 gigabytes per second
source
Daniel Lemire's blog
Decoding base64 in Python at 10 gigabytes per second
We sometimes need to convert binary data to text. For example, your emails must be stored as text files. Naïvely, you could just use a string of 0 and 1, but it would mean using one character per bit. We can do better by using 64 ASCII characters: all letters…
