Ağ yönlendiricileri için çoklu eşik kullanan geçişsiz öncelikli zamanlayıcı

Yıl 2018, Cilt: 24 Sayı: 2, 246 - 254, 30.04.2018

Tamer Dağ

Öz

Bilgisayar
ağları için mevcut ve geliştirilmekte olan çok çeşitli uygulamaların farklı
hizmet kalitesi gereksinimleri vardır. Uygulamaların ihtiyaçlarını karşılamanın
en önemli yollarından birisi ağ yönlendiricileri tarafından kullanlan paket
zamanlama algoritmalarıdır. Uygulamalara yönlendirici kaynaklarını ayırarak, paket
zamanlayıcıları uygulamaların hizmet kalitesi ihtiyaçlarını artırmaya çalışır.
Bu nedenle, gecikmeler azaltılabilir ya da uygulamaların güvenilirliği paket
kayıplarını azaltmak suretiyle arttırılabilir. Öncelikli zamanlayıcılar, yüksek
öncelikli uygulamaların gecikme ve kayıplarını azaltabilirler. Öte yandan,
düşük öncelikli uygulamalar için açlık problemi getirirler. Düşük öncelikli
uygulama paketleri aşırı gecikmeler ve kayıplarla karşılaşabilirler. Bu
makalede çoklu eşik kullanan geçişsiz öncelikli zamanlayıcı (PRMT)
önerilmektedir. PRMT zamanlayıcı farklı öncelikli uygulamalar için önceden
tanımlanmış eşik seviyeleri kullanan tek bir kuyruk ihtiyacı duyar. PRMT
zamanlayıcı yüksek öncelikli uygulamaların üzerinde önemli bir etkiye yol
açmadan,  düşük öncelikli uygulamalardaki
açlık sorunu ortadan kaldırır.

Anahtar Kelimeler

Ağ yönlendiricileri, Servis kalitesi, Öncelikli zamanlayıcı, Çoklu eşik

Non-preemptive priority scheduler with multiple thresholds for network routers

Öz

The
vast variety of applications available and being developed for computer
networks have different quality of service requirements. One of the most
significant ways to satisfy the needs of the applications is the packet
scheduling algorithms employed by the network routers. By allocating router
resources to the applications, packet schedulers try to improve the quality of
service needs of the applications. Thus, the delays can be reduced or the
reliability of the applications can be increased by reducing packet losses.
Priority schedulers are able reduce the delay and losses for high priority
applications. On the other hand, for low priority applications they introduce
the starvation problem. Low priority application packets can face excessive
delays and losses. In this paper, a non-preemptive priority scheduler with
multiple thresholds (PRMT) is proposed. The PRMT scheduler needs only a single
queue with predefined threshold levels for different priority applications. The
PRMT scheduler eliminates the starvation problem of low priority applications
without a significant impact on the high priority applications.

Anahtar Kelimeler

Network routers, Quality of service, Priority scheduler, Multiple threshold

Kaynakça

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