Second Chance Algorithm - Page Replacement - Operating System

[@Christopher-side_dude-Murican]

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

[@devarshbhatt5612]

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

[@YouKnowMeDuh]

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

[@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!

[@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???

[@jeffpenner6868]

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

[@Bedocalaway]

Best explanation of second chance on KZbin! Glad I found you 😩

[@yashtamakuwala1322]

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

[@asifnazar695]

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

[@pranayramayanapu]

always the old videos with good content

[@newschool050]

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

[@calvinlau9549]

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

[@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.

[@KageKevSama]

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

[@warrior100girl]

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

[@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.

[@khan-zv6ox]

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

[@wesskhd7]

You are the best teacher !!

[@magdam3961]

Perfectly explained! Thank you!

[@JoseAguirre-ri8tg]

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

[@backtashmohammadi3824]

Best explanation ever .

[@mickyo9223]

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

[@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)

[@jeffreydilley3380]

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

[@ApoorvaRajBhadani]

Great explanation with a great example

[@rex-qh9sy]

Awesome explanation

[@nandkishorenangre8244]

Explain very well but I found you funny haha

[@truonghuynhhoa]

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

[@yanmoenaing71]

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

[@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

[@ItsNavTheNavigator]

Only INDIAN accent :) very helpful video Thanks

[@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?

[@yellectronix]

very good explanation

[@youpyop]

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

[@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

[@Premprakash-wj9dm]

U explained perfectly, thanks.

[@RaviSharma-mh3vd]

please make playlist for separate video lecture it's awesome

[@narcispaduraru6859]

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

[@golamsarwar4540]

very clear to understand

[@DannyHudetz]

Wishing this guy was my professor instead

[@jackywong941]

will the reference bit become 2 or more?

[@ismail8973]

Thank you sir you saved my time

[@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...

[@jovan_spasovic]

Thank you so much for a great video!

[@MrKristian252]

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

[@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.....

[@perkhaahmad1136]

thank you sir its a very good lecture.

[@crazeeealgorithms3236]

very nice explanation!!!

[@muratd8428]

great teaching, thank you

[@codestorywithMIK]

Thank you. It was very helpful

[@GamjaField]

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

[@OkSear]

same thing I am wondering

[@vinayak186f3]

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

[@Emeldalala]

This was so helpful. Thank you.

[@yashbehara7525]

good explanation!.. cheers

[@iqrabhat8193]

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

[@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

[@sanikapatwardhan1590]

Thank you! Great explanation

[@tirosc]

I LOVE YOUR VOICE

[@mrpaulcreations2172]

Helpful lecture.

[@surajmehare]

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

[@cagrkaymak3063]

guys there is a mistake at kzbin.info/www/bejne/rKDMfWVjo7agorc because we put 2 to end of queue so its refererence bit must be still 1 not 0

[@lochuanchang1572]

A big mistake, When a page gets a second chance, its reference bit is cleared, and its arrival time is reset to the current time.

[@ZikoMario]

Due to this page it is not: www.mathcs.emory.edu/~cheung/Courses/355/Syllabus/9-virtual-mem/SC-replace.html Look at the 12th and 14th point starting from the beginning.

[@megadaniel1100]

To my lecture notes what lochu'an says it's right. A page who gets a second chance won't be replace till all other pages have been replaced or given a second chance . This is due to fifo

[@shivajibalijepalli565]

I think, he did the same. Didn't he? Page 2 had it's reference bit as 1. It was given a second chance when 5 had to be brought in. 5 was brought in, in place of 3. The reference bit of page 2 was made as 0. Did he not do it at a later point of the problem for a different instance?

[@megadaniel1100]

@@shivajibalijepalli565 It is Fifo order and the get a set in fifo order. When they get second chance bit is cleared and page arrival time is set to current time.

[@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

[@shuangli5466]

The indian accent make it that much better

[@xiaoyanqu9917]

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

[@Noshdudee]

great video! thanks for the help

[@AmanKumar-tu2og]

Thanks! Helped a lot!

[@valkon_]

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

[@cosma_one]

mamalis is love. mamalis is life.

[@katherinelim187]

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

[@ritikeshsingh5940]

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

[@umeboshi_]

Thank you for making indonesia subtitle sir

[@benaloney]

Cheers Bud!

[@kirtipaldayma8446]

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

[@viplovemahi1852]

Lru approximation is same as sca?

[@hesahesa5665]

thaks very much i am understand this easy

[@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|

[@hautrinh3139]

Thanks teacher

[@143Pcrish]

Good job

[@Mike-vj8do]

Thank you very much

[@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 .

[@salookie8000]

well explained, thank you

[@abhijay08]

thanks bro...helped me alot

[@sarrabenabdallah3667]

Thank you 💓

[@sarojmaharjan6394]

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

[@lounesnaima7288]

thaanks you are the best!!

[@mars-d6e]

The audio quality 🥲

[@rameshpradhan2308]

I think there is mistake after time : 7:24 . Since 5 is just referenced bit of 5 should be 0 this time.

[@rameshpradhan2308]

+Ramesh Khatri ho ni bro!!!

[@rameshpradhan2308]

+Ramesh Khatri maile vaneko point dekhi wrong xa!! reference bit of 5 0 hunxa ani 5 replace hunxa!!

[@prempandey8084]

+Ramesh Shrestha thik chha bro. kina bhane tyo vandaa aghi ko case maa 2 oldest thiyo tara reference bit 1 hunaa le baachyo, ra aru replace vaye teivayera reference bit pani 0 vayo. Tara yo case maa pani oldest ta 2 nai ho ni, 5 laai ta kei darai vayena replace hune, sidhai 2 replace vaako ho 5 maa napugikanai, so tesko reference bit change vayena, yedi 5 oldest hudo ho ani, tyo chai replace hune condition aako vaye chai ghatthyo.

[@prempandey8084]

jun chai thyakkai tes pachhiko step maa vaihaalyo

[@rameshpradhan2308]

oh i am sorry!! i was wrong!! this algorithm is 100% correct

[@memoyou5493]

At second 8.21, why we replaced 4 with 2? shouldn't it be replaced with 3 cuz 3 is older than 4? thank you

[@radudunarentu4124]

+Memo salem you are right, he made a mistake.

[@prasoondavid5874]

well 3 is the latest entry !!

[@ga9526]

confusion starts at 7:06

[@fakegamer9025]

Why? Watch carefully dude

[@pujanshah4664]

Awesome.

[@GoCanucks89]

thank you vally much

[@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.

[@ImperatorM]

Very Big Mistake. It is not as easy as shown in this video. You have to think in a "clock". After 2 has got his second chance, it went to the end of the Queue, so it is not the "oldest" one, it is the "younges" one.

[@shlomibirs]

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

[@albamustafaj5454]

This is wrong, at 4:00 2 should go at the end of the table and its R bit should become 0. It shouldn't stay in the beginning of the table you are violating the rule

[@aminostemo6179]

thank you

[@kazishohel9358]

thanks bro........

[@Alextauren1]

Thanks apu

[@DestructChen]

thanks mate :)