Ağ yönlendiricileri için çoklu eşik kullanan geçişsiz öncelikli zamanlayıcı

Bilgisayarağları için mevcut ve geliştirilmekte olan çok çeşitli uygulamaların farklıhizmet kalitesi gereksinimleri vardır. Uygulamaların ihtiyaçlarını karşılamanınen önemli yollarından birisi ağ yönlendiricileri tarafından kullanlan paketzamanlama algoritmalarıdır. Uygulamalara yönlendirici kaynaklarını ayırarak, paketzamanlayıcıları uygulamaların hizmet kalitesi ihtiyaçlarını artırmaya çalışır.Bu nedenle, gecikmeler azaltılabilir ya da uygulamaların güvenilirliği paketkayıplarını azaltmak suretiyle arttırılabilir. Öncelikli zamanlayıcılar, yükseköncelikli uygulamaların gecikme ve kayıplarını azaltabilirler. Öte yandan,düşük öncelikli uygulamalar için açlık problemi getirirler. Düşük öncelikliuygulama paketleri aşırı gecikmeler ve kayıplarla karşılaşabilirler. Bumakalede çoklu eşik kullanan geçişsiz öncelikli zamanlayıcı (PRMT)önerilmektedir. PRMT zamanlayıcı farklı öncelikli uygulamalar için öncedentanımlanmış eşik seviyeleri kullanan tek bir kuyruk ihtiyacı duyar. PRMTzamanlayıcı yüksek öncelikli uygulamaların üzerinde önemli bir etkiye yolaçmadan,  düşük öncelikli uygulamalardakiaçlık sorunu ortadan kaldırır.

Non-preemptive priority scheduler with multiple thresholds for network routers

Thevast variety of applications available and being developed for computernetworks have different quality of service requirements. One of the mostsignificant ways to satisfy the needs of the applications is the packetscheduling algorithms employed by the network routers. By allocating routerresources to the applications, packet schedulers try to improve the quality ofservice needs of the applications. Thus, the delays can be reduced or thereliability of the applications can be increased by reducing packet losses.Priority schedulers are able reduce the delay and losses for high priorityapplications. On the other hand, for low priority applications they introducethe starvation problem. Low priority application packets can face excessivedelays and losses. In this paper, a non-preemptive priority scheduler withmultiple thresholds (PRMT) is proposed. The PRMT scheduler needs only a singlequeue with predefined threshold levels for different priority applications. ThePRMT scheduler eliminates the starvation problem of low priority applicationswithout a significant impact on the high priority applications.

Kaynakça

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