Tag Archives: time

微軟的 Time Service 回應錯誤的時間...

看起來會有不少災情 (像是 SQL Server 遇到使用 server side 的時間的 SQL query):「Windows Time Service is sending out wrong times and that’s a big problem」,報導裡引用了 Reddit 上「PSA: time.windows.com NTP server seems to be sending out wrong time」這邊的討論串。 為了避免這種情況,不同單位會用不同方法解決。像是財力充足的 Google 就自己搞了原子鐘,然後還放 Google Public NTP … Continue reading

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Amazon EC2 上的 gettimeofday 與 clock_gettime 的效能

看到「Two frequently used system calls are ~77% slower on AWS EC2」這篇在講 gettimeofday 與 clock_gettime 的效能,另外搜資料時發現應該也是作者提問的「gettimeofday() not using vDSO?」這篇。 在 EC2 比較新的機器上用 tsc 應該是沒問題的 (在 2015 的時候官方就這樣建議了): it seems tsc support in Xen has improved with version 4.0 and with improved … Continue reading

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DynamoDB 推出 TTL 功能

DynamoDB 推出了依照時間自動刪除的功能:「New – Manage DynamoDB Items Using Time to Live (TTL)」。 You can enable this feature on a table-by-table basis, specifying an item attribute that contains the expiration time for the item. 這個功能比較特別的是,刪除的 scan 是不收取費用的: There is no charge for … Continue reading

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Cloudflare 因為閏秒炸掉...

Cloudflare 這次閏秒炸掉:「How and why the leap second affected Cloudflare DNS」,影響範圍包括了 DNS query 與 HTTP request: At peak approximately 0.2% of DNS queries to Cloudflare were affected and less than 1% of all HTTP requests to Cloudflare encountered an error. 主要的原因在於 … Continue reading

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Google 的 time.google.com

看到這張圖在講不同 server (service) 如何處理今年的 leap second (UTC 的跨年,台灣時間早上八點),出自 leap smear 這邊: 在很早前就有 time.google.com 這個 domain,但是當時 Google 的人有跳出來說明這個服務不是公開服務 (當時),不保證這個服務的正確性與穩定性:「timeX.google.com provide non standard time」。 不過一個月前公佈出來的 Google Public NTP 服務算是把整個系統搞定了。 其中在 Configuring Clients 這邊直接推薦用 iburst 參數,不愧是家大業大的 Google XDDD: When the server is unreachable … Continue reading

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把 CSC (卡片背面的三碼) 變成 OTP (動態密碼)

把信用卡背面的後三碼 (Card security code) 變成動態密碼,雖然一般只會有三碼,但對於網路消費應該會有不少幫助,不過這樣就不能完全不拿出卡片了...:「This high-tech card is being rolled out by French banks to eliminate fraud」。 產品叫做 MotionCode,會先從法國開始: Today both Société Générale and Groupe BPCE, two of France’s largest banking groups, are preparing to roll out these cards across … Continue reading

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密碼系統的 Monoculture

這篇文章講到最近密碼系統的現象:「On the Impending Crypto Monoculture」。 目前常在用的密碼系統包括了 RSA、DH、ECDH、ECDSA、SHA-2、AES 這些演算法,而最近這幾年大家在推廣使用的演算法都出自於同一個人手裡,Dan Bernstein,也就是 djb: A major feature of these changes includes the dropping of traditional encryption algorithms and mechanisms like RSA, DH, ECDH/ECDSA, SHA-2, and AES, for a completely different set of mechanisms, including … Continue reading

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加州在規劃廢除日光節約時間

加州在規劃廢除日光節約時間:「California could drop Daylight Saving Time」。 A California lawmaker has introduced a bill to unshackle the Golden State from the horological chains of Daylight Saving Time. 主要是沒有實質效益,甚至是與當初預期的反效果: Daylight saving time is observed in about 70 countries worldwide, but its benefits … Continue reading

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Adobe Typekit 對 PageSpeed 的妥協

Adobe Typekit 是個收費的網頁字型服務,為了讓變更可以儘快生效,用了比較短的 cache time: We use a short cache time for the kit JavaScript so that you can update your kit (for example, adding fonts, or changing the list of allowed domains) and have your changes live in a … Continue reading

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