Topic 14-15. Cache memory, cache memory functions and levels. 14-15-Mavzu. Kesh xotira, kesh xotira vazifalari va darajalari

Cache memory formed reach
Cache memory this straight away appealing uncha big not hamjli high speed with running memory . U code and information pieces temporary save for designed . Cache memory memory of the field all address cover takes , but fast from memory different as a programmer for does not appear and not directed .
Cache memory build scheme

• Cache memory time and in space links locality principle on built _
• Cache controller ( controller ) data from TX and software of codes copies , size one reading cycle teng which was block cache _ loads . Processor cache - from memory words on reads _
• Cache-controller processor fast to memory queries stops and cache- in memory data real copy availability checks .

Kesh-xotirani tashkil etish
Kesh-xotira bu to’g’ridan-to’g’ri murojaatli uncha katta bo’lmagan hamjli yuqori tezlik bilan ishlaydigan xotiradir. U kod va ma’lumotlar bo’laklarini vaqtinchalik saqlash uchun mo’ljallangan. Kesh-xotira xotira sohasining barcha adreslashlarini qamrab oladi, lekin tezkor xotiradan farqli ravishda, u dasturchi uchun ko’rinmaydi va yo’naltirilmagan.
Kesh-xotirani qurish sxemasi

• Kesh-xotira vaqt va makondagi havolalar lokalligi tamoili bo’yicha qurilgan.
• Kesh-kontroller (nazoratchi) TX dan ma’lumotlar va dasturiy kodlarning nusxalarini, o’lchami bitta o’qish sikliga teng bo’lgan blokni kesh-xotiraga yuklaydi. Protsessor kesh-xotiradan so’zlar bo’yicha o’qiydi.
• Kesh-controller protsessorning tezkor xotiraga so’rovlarini to’xtatadi va kesh-xotirada ma’lumotlarning haqiqiy nusxasi mavjudligini tekshiradi.

Cache memory structure
Kesh-xotira tuzilishi
Commands and information how to be stored depending on the cache two kind of type available .
commands and data are shared stored cache- memory is called a combined cache _ _ tilida - obъedinennaya cache memory ).
Commands separately , data separately stored cache- memory esa separately is called a dedicated cache _ _ tilida - razdelennaya cache memory ).
Current on computers more separately from the allocated cache used .
Cache memory of application - one , two and three sathli options available . Three in Figure 2 layered cache- to memory has which was system listed .
Buyruqlar va ma’lumotlarni qanday saqlanishiga qarab kesh-xotiraning ikki xil turi mavjud.
Buyruqlar ham, ma’lumotlar ham birgalikda saqlanadigan kesh-xotira birlashtirilgan kesh-xotira deb ataladi (rus tilida - объединенная кэш-память).
Buyruqlar alohida, ma’lumotlar alohida saqlanadigan kesh-xotira esa alohida ajratilgan kesh-xotira deb ataladi (rus tilida - разделенная кэш-память).
Hozirgi kompyuterlarda ko‘proq alohida ajratilgan kesh-xotiradan foydalanilmoqda.
Kesh-xotirani qo‘llashning – bir, ikki va uch sathli variantlari mavjud. 2-rasmda uch sathli kesh-xotiraga ega bo‘lgan tizim keltirilgan.
First level cache memory (L1) central processor in located and he commands for (L1-I) and information designed for (L1-D) typically 16 to 256 Kbytes until size has which was separately from the allocated cache consists of.
Processor next to him one in the block located second level cache memory (L2) is 512 Kbytes to 1 Mbytes until size has to be possible both commands and data are shared _ from a stored , unified cache consists of will be .
Third level cache- memory processor located plataga installed and he is one how much megabytes size has which was static fast memory from the device (TXQ) consists of will be ( Russian) tilida - staticheskoe operative zapominayushchee ustroystvo - OZU).
Birinchi sath kesh-xotirasi (L1) markaziy protsessor ichida joylashgan bo‘lib, u buyruqlar uchun (L1-I) va ma’lumotlar uchun (L1-D) mo‘ljallangan odatda 16 dan 256 Kbayt gacha xajmga ega bo‘lgan alohida ajratilgan kesh-xotiradan iboratdir.
Protsessor yonida u bilan bitta blokda joylashgan ikkinchi sath kesh-xotirasi (L2) esa, 512 Kbayt dan 1 Mbayt gacha xajmga ega bo‘lishi mumkin bo‘lgan, buyruqlar ham, ma’lumotlar ham birgalikda saqlanadigan, birlashtirilgan kesh-xotiradan iborat bo‘ladi.
Uchinchi sath kesh-xotirasi protsessor joylashgan plataga o‘rnatilgan bo‘lib, u bir necha megabayt xajmga ega bo‘lgan statik tezkor xotira qurilmasidan (TXQ) iborat bo‘ladi (rus tilida – статическое оперативное запоминающее устройство - ОЗУ).
Figure 2. Three level cache- to memory has system
2-rasm. Uch sathi kesh-xotiraga ega tizim