Learn about latency and co-location — Hinglish notes

6.3.8 · Stock-Market › Market Microstructure

Latency KYA hai?

Woh pieces jo milkar bante hain

WHY ise tod ke dekhein? Kyunki tum sirf wahi optimize kar sakte ho jo measure kar sako. Total latency independent delays ka sum hoti hai, isliye hum ise first principles se derive karte hain — signal ki journey trace karke.

Formula Round-trip latency, derived

Ek trade decision trace karo. Signal ko:

Exchange → tumhare server tak travel karna hoga (propagation): $t_{prop,in}$
Tumhari strategy code se process hona hoga: $t_{compute}$
Tumhare server → exchange tak travel karna hoga (propagation): $t_{prop,out}$
Exchange ki queue mein wait karna hoga + match hona hoga: $t_{exch}$

Kyunki yeh sab sequence mein hota hai, total latency inका sum hai: $L_{total} = t_{prop,in} + t_{compute} + t_{prop,out} + t_{exch}$

Propagation part physics se set hoti hai. Fibre mein ek signal roughly light ki speed ke $\frac{2}{3}$ par travel karta hai: $v_{fibre} \approx \frac{c}{1.5} = \frac{3 \times 1 0 ^{8}}{1.5} = 2 \times 1 0^{8} m/s$ Toh distance $d$ par one-way propagation delay hai: $t_{prop} = \frac{d}{v _{fibre}}$

Yeh kyun matter karta hai: distance woh EK term hai jise tum physically paas jaake slash kar sakte ho — yahi co-location hai.

Co-location KYA hai?

Figure — Learn about latency and co-location

Edge KAISE compute karte hain? (Worked examples)

Common mistakes (Steel-manned)

Recall Feynman: 12-saal ke bache ko samjhao

Socho ek class hai jahan jo sabse PEHLE sahi jawab chillata hai use prize milta hai. Teacher ek hint whisper karti hai. Agar tum room ke peeche baithe ho, toh awaaz tumtak pahunchne mein zyada time lagta hai, isliye front row ka bachcha hamesha pehle chillata hai. Co-location matlab teacher ke bilkul paas, front row mein baithe ke liye pay karna hai. Lekin front row mein bhi, agar tum slowly sochte ho (slow computer/code), toh do rows peeche baitha faster-sochne wala bachcha tumhe phir bhi beat kar sakta hai. Aur chahe tum kitne bhi paas baitho, awaaz aane mein thoda time lagta hi hai — literally zero time par react karna kabhi possible nahi hai.

Flashcards

Market microstructure mein latency kya hai?

Ek market event ke hone aur trader ke order ke exchange tak pahunchne (aur process hone) ke beech ka total time delay, ms/µs/ns mein measure kiya jaata hai.

Co-location kya hai?

Exchange ke data centre ke andar server space rent karna taaki matching engine tak physical distance — aur isliye propagation delay — minimize ho jaaye.

Exchanges co-located clients ko equal-length cables kyun dete hain?

Taaki sabhi paying clients ke liye propagation delay identical rahe, isliye advantage hardware/code par depend kare, physical rack position par nahi.

Fibre optic cable mein signal ki approximate speed kya hai?

Lagbhag

2 \times 1 0^{8}

m/s, vacuum mein light ki speed ka roughly two-thirds.

Fibre mein distance d par one-way propagation delay ka formula?

t_{p r o p} = d / v = d / (2 \times 1 0^{8} m/s)

Round-trip latency ke chaar sequential components kya hain?

Propagation-in + Compute time + Propagation-out + Exchange queue/matching time.

Latency vs bandwidth — kya farq hai?

Latency delay hai (time per message); bandwidth throughput hai (data volume per second). HFT ko latency ki chinta hoti hai.

Firms shehron ke beech fibre ki jagah microwave links kyun use karti hain?

Microwaves hawa mein c ke paas (3×10⁸ m/s) travel karte hain aur seedha rasta lete hain, jo fibre (2×10⁸ m/s) se kam propagation delay deta hai.

Kya latency zero tak reduce ho sakti hai?

Nahi — light ki speed ek hard floor hai, plus compute aur exchange-queue times kabhi poori tarah vanish nahi hoti.

400 km par one-way fibre delay?

t = 400, 000/ (2 \times 1 0^{8}) = 2 ms

Connections

Market Microstructure
High-Frequency Trading
Order Matching Engine
Bid-Ask Spread
Speed of Light
Fibre vs Microwave Networks
Fairness in Electronic Markets