So it occurred to me that for some time I've been saying that BFS may scale well only up to about 16 CPUs. That was a fairly generic guess based on the design of BFS, but it appears that these more-thread machines and multi-core machines seem to quite like BFS on the real-world benchmarks I'm getting back from various people. With the latest changes to BFS, which bumped the version up to 0.400, it should have improved further. I've tried googling for links to do with BFS and scalability and the biggest machine I've been able to find that benefits from it is a 24 core machine running F@H (folding at home). Given that this was with an older version of BFS, and that there were actually advantages even at 24 cores, I wonder what the point is where it doesn't scale? Obviously scalability is more than just "running F@H" and will depend entirely on architecture and workload and definition of scalability, and so on, but... I wanted to ask the community what's the biggest machine anyone has tried BFS on, and how well did it perform? If someone had access to 16+ cores to try it out I'd be mighty grateful for your results.
Sorry mate, I only have 2 cores here. I blogged about your request though. I will try asking a friend of mine who has 20 or so cores on his machine.
Ive skimmed over your code, I think you have a lock on each process in the runqueue, and on the runqueue itself. Could you not use an atomic compare and swap on the processes lock and so ignore the runqueue lock? That would allow multiple CPUs to access the queue without waiting.
There is no meaningful process lock, only the runqueue lock. The runqueue lock contention is the most likely culprit for a scalability limit here since it's a shared runqueue. Atomic compare and swap would be extraordinarily painful to use here because you'd look over a list, and processes would be disappearing all the time onto other CPUs so you'd have to re-check it was still there every time you went back to the task you had chosen if you had not already taken it. The whole design would have to be rewritten from scratch to do so and the multiple checking of the existence of the process each time would greatly increase the overhead in the non-contended case - which is the target audience for BFS as it was designed for commodity hardware and desktops. Lower CPU count machines already show less overhead with BFS than mainline, but I've been unable to test 16x or more. The scheduler overhead cannot be measured in ms but in nanoseconds. Runqueue contention was demonstrable as occurring on the 8x with a load of 1000 but was still not contributing significantly in overall time compared to any other lock in the kernel. I estimated once that lock contention would be relevant from 16 CPUs but that was an arbitrary figure that I didn't have hardware to prove it on. As mentioned, the fact it shows scalability outstripping mainline at 24 CPUs suggests the limit is somewhat beyond that. No doubt when the number of CPUs becomes very high the contention becomes relevant.
Thankyou for such a quick response. Would you happen to have any technical docs on how bfs work as i would love to read anything on it.
Just some feedback on your posts. So i guess that you run over the whole list first, deside on the best task. And then allocte it to the cpu? (..will post more in the morning)
Sure,the patch itself has documentation in it. When patched in it will appear in Documentation/scheduler/sched-BFS.txt
The situation on the screenshot is quite typical. When the load increases - is activated 6-e kernel.
@VamPiro: I'm not sure what you're trying to tell me, sorry. I see lots of nice -20 tasks running but I can't see anything else.
I have an i7 920 running Gentoo amd64 w/ HT (so 8 cores). Feel free to give a holler on IRC if you need testcases run on this hardware and I'd be more than happy to.
It's very hard for me to objectively tell the difference. Especially lately I notice very little difference in {C,B}FS. My feeling just from staring at htop is BFS gives slightly better throughput on big compiles.
Thanks Ormaaj. Found someone with access to a 24 core AMD machine and he's kindly offered to do some benchmarks. The results so far are promising :)
CK Cabinetry and Design can assist you with all aspects of your remodel right down to the last detail; design of the space, cabinetry, decorative hardware, counter tops, tile, backsplashes, plumbing fixtures, grout selection, color consulting, contracting, project management. We are with you from start to finish to ensure your project runs smoothly and you get exactly what you dream of.
Projects come in all shapes and sizes. C K Cabinetry and Design has assembled a top notch team of licensed bonded and insured tradesman to bring your vision to life.
Carlie worked with us during the spring and summer of 2013 on a major remodel of our home. Carlie was responsible for the design of the project, selection of materials and equipment, scheduling, and budgeting. She helped us with all aspects of the project. Our remodeling project turned out to be rather extensive. Major emphasis was on the kitchen/family room, a powder room, and the master bathroom. In the kitchen/family room area we replaced the cabinets, counter-tops, appliances, flooring, lighting, fans, cornices, and repainted. Carlie served as the designer for the entire project. This included helping us think through the best layout for the kitchen, the appliances and their location, the countertops, the plumbing, the lighting, the floor tiles and the paint. In the master bath we ended up removing the bathtub, toilet, bidet, walls, and all of the vanity area and started over. Again, Carly provided invaluable advice and help. She had great ideas, and we probably would not have gotten the wonderful "total package" without her assistance. We were particularly pleased with our new walk in shower. We had to leave for 6 weeks as the project was reaching completion. We had complete confidence in Carlie and were able to communicate with her and allow the project to be completed while we were in Maine. In addition to being very creative, Carly is very well organized and can be counted on to follow through on projects. We are very pleased with the results and give much of the credit to Carlie. We would not consider using any other designer for future projects.
Carlie took my 12-year old, cramped and cluttered kitchen and turned it into a spacious, light filled, high functioning space. She accomplished this by applying her great design vision and decades of practical expertise. Paying attention to workflow and understanding my design objectives, she carved out new seating space while adding counter and storage capacity. I particularly liked her ability to either improve upon my choices – or to diplomatically steer me towards better solutions. Carlie worked with a top team which included her own people as well as a fantastic contractor and suppliers. I would happily recommend her for any job, and look forward to working with her again on my other remodeling projects.
We sought Carlie Korinek’s help in help in creating a new bathroom. Our bathroom was dated. We wanted more lights, more plugs, new material for our counter tops, a large tub, a larger shower. With just this information, she created a masterpiece within our budget. She worked tirelessly with us and vendors to get the things we wanted at our price. She also designed some original cabinetry to give us more space. People are amazed with such an original creation. I would highly, highly recommend Carlie for any remodeling projects.
What a pleasure to work with CK Cabinetry and Design. They are caring, consummate professionals embodying everything a homeowner could want to make their kitchen into an outstanding "dream" kitchen. No stone remains unturned in their quest to help in every way. From design options, budgetary considerations and expert knowledge of their products to the superb quality and care present during every step of the installation. We couldn't be more pleased. We give them our highest recommendation.
I knew what I wanted in my new kitchen design and Carlie listened to my dream. She is very professional and honest when. going over the details. she delivered my dream Kitchen and stayed in budget. I would recommend her to anyone!
I have had Carlie Korinek in my design classes since 1999. She was an excellent student who went to school full time and, at the time, held a full time job as a kitchen designer.	Carlie displays the traits that will make her a valuable member to ASID. She is a good kitchen designer, has an excellent sense of her ethical duty to her profession and is eager to volunteer her time to the growth and understanding of interior design.
Canada Vista Homes is a high-end semi-custom home builder. We design and build 25+ homes per year in the 2400sf-3400sf range. All of our kitchen and bath cabinets designs and installations are performed by our subcontractor and Carlie is our design person and she handles all of our homes. She meets with our customers to custom design their kitchens and baths, assists them with their cabinet selections and measures and orders the cabinets. In all instances she has performed in a cheerful and professional manner. She has been extremely capable and creative in her designs and has received high praise for our customers. Carlie has grown to be a great asset allowing us to turn over the total process of cabinet design, selection and installation to her.
Carlie is very pleasant to be around. She always takes the time to listen and help the customers accomplish what they want in a professional manner. She understands the limits of a buyer and that a builder asks for and does a good job working within those limits. She does a good job in layout and design and coming up with fresh ideas. She is a joy to work with.
Carlie demonstrates the skills and creativity that both our clients and we have come to appreciate. She has been a problem solver and a great troubleshooter in situations where customer’s expectations may have been unrealistic. We have been completely satisfied with Carlie’s prompt response, customer service and the end result. Delivery times, installations and product quality have also been more than satisfactory. We would highly recommend Carlie
Dear Carlie and Mike (Granite Kitchen and Bath) About time I sent word to you both regarding our immense satisfaction with the end result of our Tucson kitchen update.Carlie, you are aware of Jim’s enthusiasm with moving ahead and a bit of my reluctance. Showing up with a fractured fibula early this year, kitchen decisions were not high on my priority list. But…. Jim persevered and with your help decisions were reached, deposits were made and the deadline was determined. Your ideas, discussions and suggestions were invaluable as was your helpful manner. (We love the soft closing drawers! And pots/pans drawers.) With some luck researching your list of granite installers, we caught up with Mike who had nothing but praise regarding working with Carlie. We thank you both for working together and trying to meet our departure deadline. Mike, the suggestion for granite behind the sink, the ledge above the installation is proof of your skills. To add to our trust in your people, Jim left for the airport with the men still working on the granite (drilling holes for the soap dispenser, faucet and disposal) asking them to lock the door behind them when they left. How often does that happen? I thank you both for an updated kitchen completed to our satisfaction. I could not be happier with the end result. You work well as a team.
We have just “moved” to our new house a couple of weeks ago and I did not want the whirlwind of the move to delay my sending this letter any longer. I wanted to thank you and your company for doing a terrific job with our cabinets. Our experience started with meeting Mrs. Carlie Korinek, who was very professional and knowledgeable and personable. She helped us choose the style and color that matched our house’s architecture and designed a wonderful layout for our kitchen and bathrooms. We are very glad we chose you to do our cabinetry, it looks and works great! And, we are very thankful to our builder who recommended you,
I am writing to let you know how pleased we are with the kitchen that Carlie Korinek designed for us. Our home had sustained water damage and we decided that we were going to remodel our home. We knew that we wanted to replace the kitchen cabinets and knock out a wall between the dining room and kitchen. We also knew that we would replace the bathroom vanities. Carlie worked with us to determine what was important to us and drew a plan that utilized the space to advantage. She also was extremely helpful concerning questions I had regarding lighting needs for the kitchen, countertop options and color choices. My husband and I needed a neutral voice on some of our decisions and Carlie worked with us so that we were both happy with our choices. Oh, and to add to the project, the home we were remodeling was in Green Valley, we only spent about seven nights in the house, and we live in Phoenix. Again, Carlie was able to offer suggestions as to where in Tucson we could look for plumbing, lighting, etc. I would recommend Carlie to anyone that is considering remodeling or building. She was excellent to work with.
Quick note to let you know u did an outstanding job handling all the details regarding my vanity purchase! It was fast, looks good and you returned my calls to handle all the follow-up. Great Job! I wish all my suppliers are even ½ as good.
Carlie, What can I say? I so enjoyed working with you. You are a person of integrity and that is the highest compliment I could give anyone. Thanks for all your help. We love the kitchen.
Carlie Korinek did two projects for me. The first was a kitchen remodel/upgrade involving the installation of granite counter tops, some cabinet refurbishment, and the installation of new appliances. The second, in a cordial collaboration with Valley Development construction company, was a substantial bathroom remodeling involving a complete redesign of the existing space, the use of a rare blue granite, and high-end bathroom fittings. For both projects her work was outstanding: excellent design ideas that were sensitive to this client's wishes and budget, meticulous attention to detail, and total commitment to customer satisfaction. The job was not considered done until the customer was completely happy!
Money well spent briefly describes our experience with CK Cabinetry and Design. I first contacted Carlie in June of 2014 to help with the redesign of our kitchen. I had done some drawings, but never having gone through the process, was pretty overwhelmed. Carlie came to the house, took measurements, and within two weeks had 10-15 beautiful renditions of what could be our kitchen. Carlie delivered our dream kitchen on budget and on time. Because of her attention to detail, there were no problems with the installation of our cabinets or appliances. Furthermore, there were no unforeseen costs. I absolutely love walking into this space each and every day. I would definitely use her services in the future. See "grey kitchen" for pictures her design. The first photo I posted is the before and the second is the after.
Carlie from CK cabinetry and design came to my house to help with a redesign of a bathroom. Carlie had such fantastic ideas about color and textures. The bathroom could not be expanded, but she made such great use of the space I had. The tile suggestion and shower ideas were perfection! She combined white curved oblong tiles with beautiful blue and green mini tiles that accented the shower, and the sink area, perfection. Over the sink she helped me pick out a gorgeous Chandelier that made the small bathroom very glamorous, which was exactly what I wanted. Carlie was so patient with me.....I did change my mind on colors right at first, but she narrowed in on what I wanted rather quickly! The contractors she hired were so respectful of me and my family, which I think reflects on Carlie's knowledge of personalities. Very important when someone you don't know is coming into your house! I will hire Carlie with CK designs again in a heartbeat!
We are writing this letter to express our sincere thanks and compliments for a job very well done on our recent kitchen remodel. We have remodeled many of our own homes over the past few years and done much of the work ourselves. Some of our experiences with outside contractors when we had to use them have not been very good. Needless to say, we were skeptical we first set foot in the showroom. Now that we look back on the experience, we had no reason to be concerned. The entire months-long process – from the initial greeting by the receptionist, through all the discussion and interactions with designer Carlie Korinek and the visits to our home from the people who did the work, went much more smoothly than we had ever expected. Carlie was a gem. She was not only creative in helping us with the remodel designs and tailoring to accommodate Paulette’s handicap, but showed excellent skills in planning and coordinating the actual remodeling effort (and keeping us calm through the process!).
We wanted to tell you how much we appreciate your design expertise. We are so happy with our entire remodel. Love our kitchen!Thank you
In summary: Carlie provided me with the WOW factor I was looking for in my bathrooms and bedroom. I tried some things I never knew about such as venetian plaster walls, frosted glass panels and of course my chandelier. Because of her vision, I decided to go ahead with the entire downstairs of my home. She always kept my finances in mind.Carlie has integrity and tremendous vision. I would highly recommend Carlie!