Second Chance Algorithm - Page Replacement - Operating System

In this video, we learn the second chance algorithm for page replacement.
C programming series: • Introduction to Pointe...
C++ programming series: • Reference in C++ (Epis...

[@Christopher-side_dude-Murican]

Great teacher. Clear, concise and with enthusiasm. What a blessing; rare to find even decent teachers around anymore.

[@YouKnowMeDuh]

You, sir, gave *me* a second chance to actually learn this so I can properly implement it in my program. Thanks a ton!

[@devarshbhatt5612]

Great lecture sir, you literally save me around 35 mins of online lectures.

[@jeffpenner6868]

Very detailed analysis. Thanks for the lesson on second chance (clock) algorithm.

[@Bedocalaway]

Best explanation of second chance on UA-cam! Glad I found you 😩

[@KageKevSama]

Thank you that helped me out a lot. Very straightforward and comprehensive.

[@calvinlau9549]

Very clear explanation, good use of visuals. Thank you for this video!

[@YanuarTriAdityaNugraha]

good thing i've found this! i hope it helps me on OS exam :(

[@YouKnowMeDuh]

I hope it did, I got an OS program about this that I still need to finish lol!

Im from Mexico, you have amazing skills for tech, thank you very much , i watch a lot of videos, and yours it the only one that i understand at 100%

[@BBarters]

Muchisimas Gracias, es muy amable por ti parte!

[@magdam3961]

Perfectly explained! Thank you!

[@yashtamakuwala1322]

Thanks a lot Sir. You explained it better than our reference book's explanation.

[@mickyo9223]

Well put. The words at the bottom helped a lot as well. Thank you for a clean video.#allTheWayFromTexas

[@asifnazar695]

Perfect understanding so i appreciate and u r good teacher for the nation

[@newschool050]

awesome description .. and thanks for saving me for my mid sem exam

Thank you so much for a great video!

[@ApoorvaRajBhadani]

Great explanation with a great example

[@Emeldalala]

This was so helpful. Thank you.

[@Premprakash-wj9dm]

U explained perfectly, thanks.

[@warrior100girl]

thanks man! Still a chance to pass my OS exam. :D

[@AmanKumar-tu2og]

Thanks! Helped a lot!

[@Noshdudee]

great video! thanks for the help

[@sanikapatwardhan1590]

Thank you! Great explanation

[@wesskhd7]

You are the best teacher !!

[@JoseAguirre-ri8tg]

Thank you very much, this helped me clear my doubts.

[@truonghuynhhoa]

thanks for this lesson, it's very useful for me in the exam

[@abhijay08]

thanks bro...helped me alot

[@muratd8428]

great teaching, thank you

[@codestorywithMIK]

Thank you. It was very helpful

[@yashbehara7525]

good explanation!.. cheers

[@rex-qh9sy]

Awesome explanation

[@salookie8000]

well explained, thank you

[@backtashmohammadi3824]

Best explanation ever .

[@crazeeealgorithms3236]

very nice explanation!!!

[@jeffreydilley3380]

Nice work, concise, easy to understand! Thank you, as an American I appreciate how well you explain and how clear your english is :)

[@perkhaahmad1136]

thank you sir its a very good lecture.

[@pranayramayanapu]

always the old videos with good content

[@Taragurung]

So the reference bit is set to 1 only when there is page hit . ? if there suppose 5 got second chance and after that we have to replace another bit which is completely new and not in the frame. So we go through FIFO in that or which page will get a second chance

[@kirtipaldayma8446]

awesome work!!!!!!!!!!!!!11

[@golamsarwar4540]

very clear to understand

[@benaloney]

Cheers Bud!

[@nandkishorenangre8244]

Explain very well but I found you funny haha

[@ismail8973]

Thank you sir you saved my time

[@yellectronix]

very good explanation

[@mrpaulcreations2172]

Helpful lecture.

[@GoCanucks89]

thank you vally much

[@kishanchand8456]

@BBaters ,in 3'rd last table , search will start from old to new (since it is arranged in FIFO) and among 4,5,and 3 (in previous table) 4 is oldest .search will stop at 4 only.and 5 's R bit will remain 1.

[@khan-zv6ox]

xbr 10 sir ,,,, help me alot ,, thanks alot from pakistan ,,,,

[@lounesnaima7288]

thaanks you are the best!!

[@hesahesa5665]

thaks very much i am understand this easy

[@RaviSharma-mh3vd]

please make playlist for separate video lecture it's awesome

[@Mike-vj8do]

Thank you very much

[@linuscastelino]

What happens when all the candidates have their reference bits set to 1?
For example :
Input - 1 2 3 4 4 3 2 1 5
Frame size - 4

[@tuxedotroll4707]

@raj sharma and set all the ref bits to 0, right?

[@muhammadmoaazbinsajjad2029]

All the reference bits get set to 0. Then FIFO applied. In your example, 1 will be replaced.

[@tutorialsviewers1381]

Helpfull :)

[@samansingh1564]

There is an error here after 5:05. When Page 4 is to be brought into memory, the pointer that acts as head of round-robin replacement(i.e. from where we start the replacement Algo) points at Page 1 and hence, the reference bit of Page 2 will not be changed since Page 1 will be replaced immediately!
Refer : www.mathcs.emory.edu/~cheung/Courses/355/Syllabus/9-virtual-mem/SC-replace.html

[@denissssss8579]

Saman Singh r u sure???

[@hautrinh3139]

Thanks teacher

[@MrKristian252]

Does *all* of them get reset?
Is this a 1 bit value (value between 1 and 0) ?

[@sarrabenabdallah3667]

Thank you 💓

[@byeonggonlee8569]

very helpful

[@jackywong941]

will the reference bit become 2 or more?

[@smalltugz]

my teacher says when a new frame is entered the ref bit is set to one what kind of variation is that if it is right

[@pujanshah4664]

Awesome.

[@DestructChen]

thanks mate :)

[@143Pcrish]

Good job

[@iqrabhat8193]

i can say it z one of the bst video in replacmnts..
thankx a lot sir

[@yveschen404]

why the ninth page 5's reference bit is still set to 1 ? 2 is already set to 3 , doesn't set the 5's reference bit to 0? sorry about my poor language

[@orzn100]

陳奕甫 幹認真喔

[@Morocco4e]

because we didn't need to apply the second chance property we used normal FIFO

[@kazishohel9358]

thanks bro........

[@MB-pt8hi]

I think there is a big mistake. When R of B is 1 and you reset it to 0, then you have to move B to the tail of the list (see Book of Tanenbaum Page 212)

[@tirosc]

I LOVE YOUR VOICE

[@xiaoyanqu9917]

When the first "4" comes, why did you bother "2" and check the reference bit ("2" was the "last" in)?

[@ritikeshsingh5940]

What if all pages have 1 as a reference bit ? Please answer

[@aminostemo6179]

thank you

[@ItsNavTheNavigator]

Only INDIAN accent :) very helpful video Thanks

[@youpyop]

at second 7:27/9:45, why frame 5 still have 1? thank you

[@viplovemahi1852]

Lru approximation is same as sca?

[@khan-zv6ox]

anyone. why the reference bit again set 1 for 5 in second line B/C there is page fault (2 replace with 3). so we need to change the reference bit of 5 to 0??????? please any one .. so confuse...

[@Alextauren1]

Thanks apu

[@DannyHudetz]

Wishing this guy was my professor instead

[@youtubekumar8590]

Thank£

[@vinayak186f3]

My prof taught us to set the bit as 1 initially while inserting ,if I follow that way the sequence isn't same

[@yavuzkagantopak1854]

thank you sir !!!

[@rasihonurolgun4116]

no problem man its pleasure :)

[@yavuzkagantopak1854]

The "1stPC LAB TROL" is everywhere... :D

[@shibamdebnath683]

In the 7:06th minute reference bit for 5 should have changed to 1 right ? after replacing 2 with 3 in first row. Please confirm

[@VimalKumarAB]

Yes. So totally 8 page faults occur right?

[@narcispaduraru6859]

spacchi come la merda ...you saved my life dude ... india rulz

[@katherinelim187]

I suggest to make ur accent clear.. btw ur the best explanator hahaha!

[@sarojmaharjan6394]

in fifth and sixth iteration .....what if we have 3 and 3 instead of 5 and 2?

[@BBarters]

yousri mami frame 5 is still there because, its reference bit is set to 1....when a frame's reference bit is set to 1, it doesn't get replaced instead its given one more chance at the expense of setting its reference bit to 0 making it eligible for replacement next time.

[@_-ghost-_711]

but when 3 gets added at 7:24 all the reference bit should be set to 0......but u have set reference bit of 5 to 1......please explain.....

[@apostolosmavropoulos177]

thnks!

[@GamjaField]

What if same page is referenced twice? will the reference bit remain 1?

[@OkSear]

same thing I am wondering

[@vinayvyraveraja7102]

hi good job for this video, can you come up with LRU-least used algorithm for the same example TQ

[@BBarters]

Its here: Study Other Page Replacement Algorithms: bbarters.com/blogBookPreview/14

[@msalvi6302]

@@BBarters If an entry is saved due to its ref_cnt being non-zero, and when there is a hit on it again, shouldn't that be considered into making the entry younger? Which means even though it came first its not older anymore because it got hit recently. With your algorithm the second hit is not considered in updating the age of the entry. I believe the entry should be marked younger .

[@iamatal333]

Say, all the frames have their reference bit set to 1. Now which one is kicked out ? And what happens to the reference bits of the other frames, the frames that aren't removed ??

[@joe624p]

Frame 1| 1 R=1| Frame1| 1 R=0|
Frame 2| 2 R=1| then Frame2| 2 R=0| 1 is replaced
Frame 3| 3 R=1| Frame3| 3 R=0|

[@valkon_]

Nice video, but what if we have a modified bit also?

[@cosma_one]

mamalis is love. mamalis is life.

[@ankitathakur5989]

tnq sir ji

[@yanmoenaing71]

Why Indians explain so good......?

[@manish.periwal]

reference bit of 5 when 3 comes in the (9th number) should be set to 0,since there was a page fault.

[@MusicGuy423]

I don't believe that's the case since 5 is not the number that is going to be replaced. Since 2 was the first number in, 2 is going to be replaced so 5 and its reference bit is not affected

[@surajmehare]

very nice explanation which is not given in to few good books.

[@luigilantin3126]

legit!

[@AKLESHKUMAR-dr3vm]

sir you have done a small mistake when 9 th page replacement when 4 will came then 3 will be out bcz 3 is the oldest not 4.

[@shuangli5466]

The indian accent make it that much better

[@shlomibirs]

If I didn't miss something, no explanation how to know which page is older than those whose look is marked with 0

[@cagrkaymak3063]

guys there is a mistake at ua-cam.com/video/voiL2-nQmlU/v-deo.html because we put 2 to end of queue so its refererence bit must be still 1 not 0

[@pradipbhattarai5840]

what about the time?? Don't it matters?