Brendan Gregg

SEPTEMBER 25, 2021

A Cassandra database cluster had switched to Ubuntu and noticed write latency increased by over 30%. As (C) looked like a kernel rebuild, I started with (D) and (E). ## 5. As I'm interested in the relative comparison I can just compare the total runtimes (the "real" time) for the same result. Try changing the kernel clocksource.

Speed 126

Speed Java AWS Virtualization 126

Highly Scalable

SEPTEMBER 18, 2012

Historically, NoSQL paid a lot of attention to tradeoffs between consistency, fault-tolerance and performance to serve geographically distributed systems, low-latency or highly available applications. Read/Write latency. Read/Write requests are processes with a minimal latency. Data Placement. Read/Write scalability.

Database 213

Database Latency C++ Scalability 213

HammerDB

OCTOBER 23, 2023

HammerDB has always used stored procedures as a design decision because the original benchmark was implemented as close as possible to the example workload in the TPC-C specification that uses stored procedures. Additionally, reviewing official TPC-C full disclosure reports highlighted that all vendors also use stored procedures.

Benchmarking 62

Benchmarking Database Network C++ 62

Brendan Gregg

OCTOBER 8, 2018

Screenshot: tracing read latency for PID 181: # bpftrace -e 'kprobe:vfs_read /pid == 30153/ { @start[tid] = nsecs; } kretprobe:vfs_read /@start[tid]/ { @ns = hist(nsecs - @start[tid]); delete(@start[tid]); }'. Here's a comparison for an average-sized DTraceToolkit script (seeksize.d) ply is also C, whereas bpftrace is C++. #

C++ 110

C++ Virtualization Programming Latency 110

The Netflix TechBlog

JANUARY 24, 2022

Technically, “performance” metrics are those relating to the responsiveness or latency of the app, including start up time. While test metrics and metrics collected during real use do not lend themselves to direct comparison, measuring the relative change in metrics in pre-production builds can help us to anticipate regressions in production.

Performance 199

Performance Metrics Performance Testing Testing 199

Brendan Gregg

AUGUST 8, 2017

TABLE OF EXP(-T/C) FOR T = 5 SEC. EXPFF: EXP 0.920043902 ;C = 1 MIN EXP 0.983471344 ;C = 5 MIN EXP 0.994459811 ;C = 15 MIN. Some people have found values that seem to work for their systems and workloads: they know that when load goes over X, application latency is high and customers start complaining.

Latency 111

Latency Metrics C++ Systems 111

Brendan Gregg

SEPTEMBER 25, 2021

A Cassandra database cluster had switched to Ubuntu and noticed write latency increased by over 30%. As (C) looked like a kernel rebuild, I started with (D) and (E). As I'm interested in the relative comparison I can just compare the total runtimes (the "real" time) for the same result. us on Centos and 0.68

Speed 52

Speed Java AWS Virtualization 52

Alex Russell

MAY 9, 2022

This is a complex topic, but to borrow from a recent post , web performance expands access to information and services by reducing latency and variance across interactions in a session, with a particular focus on the tail of the distribution (P75+). Consistent performance matters just as much as low average latency.

Performance 86

Performance Latency Metrics Engineering 86

The Morning Paper

AUGUST 29, 2019

We group the DBMS design choices and tradeoffs into three broad categories, which result from the need for dealing with (A) external storage; (B) query executors that are spun on demand; and (C) DBMS-as-a-service offerings. Key findings. Query restrictions. Neither Spectrum nor Athena could run the full TPC-H query suite.

Architecture 76

Architecture Cloud Storage Serverless 76

Brendan Gregg

SEPTEMBER 25, 2021

A Cassandra database cluster had switched to Ubuntu and noticed write latency increased by over 30%. As (C) looked like a kernel rebuild, I started with (D) and (E). ## 6. As I'm interested in the relative comparison I can just compare the total runtimes (the "real" time) for the same result. Try changing the kernel clocksource.

Speed 40

Speed Java AWS Virtualization 40

Brendan Gregg

OCTOBER 7, 2018

Screenshot: tracing read latency for PID 181: # bpftrace -e 'kprobe:vfs_read /pid == 30153/ { @start[tid] = nsecs; } kretprobe:vfs_read /@start[tid]/ { @ns = hist(nsecs - @start[tid]); delete(@start[tid]); }'. Here's a comparison for an average-sized DTraceToolkit script (seeksize.d) ply is also C, whereas bpftrace is C++. #

C++ 40

C++ Virtualization Programming Latency 40

The Morning Paper

DECEMBER 8, 2019

Therefore any programming abstraction must be low latency and the kernel needs to be kept off the path of persistent data access as much as possible. The Twizzler KVS (key-value store) is just 250 lines of C code, and uses one persistent object for the index structure, and a second one for the data.

Hardware 56

Hardware Programming Media Storage 56

HammerDB

OCTOBER 12, 2018

This post complements the previous best practice guides this time with the focus on MySQL and MariaDB and achieving top levels of performance with the HammerDB MySQL TPC-C test. SELECT DISTINCT c from sbtest where id between ? order by c. SELECT c from sbtest where id=? Copyright (C) 2003-2018 Steve Shaw.

Best Practices 40

Best Practices Scalability Performance C++ 40

John McCalpin

JANUARY 22, 2018

Each of the two vector units can issue one FMA instruction per cycle, assuming that there are enough independent accumulators to tolerate the 6-cycle dependent-operation latency. Using the minimum number of accumulator registers needed to tolerate the pipeline latency (12), the assembly code for the inner loop is: B1.8: 8.056 0.056 75.0%

Latency 40

Latency Hardware Code Testing 40

Percona

MAY 2, 2023

Mongodump: [root@ip-172-31-37-92 ~]# time nohup mongodump -d test -c collG -o /mongodump/ & [1] 44298 [root@ip-172-31-37-92 ~]# sed -n '1p;$p' nohup.out 2020-08-26T12:36:20.842+0000 writing test.collG to /mongodump/test/collG.bson 2020-08-26T12:51:08.832+0000 [####.]

Best Practices 52

Best Practices Database Storage Servers 52

Smashing Magazine

JANUARY 11, 2021

Alternatively, you can also use: Addy Osmani’s Chrome UX Report Compare Tool , Speed Scorecard (also provides a revenue impact estimator), Real User Experience Test Comparison or SiteSpeed CI (based on synthetic testing). Estimated Input Latency tells us if we are hitting that threshold, and ideally, it should be below 50ms.

Performance 145

Performance Cache Media Metrics 145

Highly Scalable

MAY 1, 2012

This approach often leads to heavyweight high-latency analytical processes and poor applicability to realtime use cases. This process is shown in the figure below: It is clear that if sketch is large in comparison with the cardinality of the data set, almost each value will get an independent counter and estimation will precise.

Analytics 191

Analytics Traffic Big Data Efficiency 191

Brendan Gregg

SEPTEMBER 5, 2017

Here's some output from my zfsdist tool, in bcc/BPF, which measures ZFS latency as a histogram on Linux: # zfsdist. Tracing ZFS operation latency. Hit Ctrl-C to end. ^C Oracle have a similar useful page as well: the Linux to Oracle Solaris 11 comparison, as well as a [procedure] for migrating from Solaris to Linux.

Virtualization 76

Virtualization AWS Engineering Hardware 76

Smashing Magazine

JANUARY 7, 2019

To get a good first impression of how your competitors perform, you can use Chrome UX Report ( CrUX , a ready-made RUM data set, video introduction by Ilya Grigorik), Speed Scorecard (also provides a revenue impact estimator), Real User Experience Test Comparison or SiteSpeed CI (based on synthetic testing).

Performance 103

Performance Cache Metrics Network 103

Smashing Magazine

JANUARY 6, 2020

Alternatively, you can also use Speed Scorecard (also provides a revenue impact estimator), Real User Experience Test Comparison or SiteSpeed CI (based on synthetic testing). Paddy Ganti’s script constructs two URLs (one normal and one blocking the ads), prompts the generation of a video comparison via WebPageTest and reports a delta.

Performance 145

Performance Cache Network Metrics 145

Smashing Magazine

AUGUST 22, 2021

Because we are dealing with network protocols here, we will mainly look at network aspects, of which two are most important: latency and bandwidth. Latency can be roughly defined as the time it takes to send a packet from point A (say, the client) to point B (the server). Two-way latency is often called round-trip time (RTT).

Performance 105

Performance Network Latency Servers 105

SQL Server According to Bob

JANUARY 11, 2020

The caching of data pages and grouping of log records helps remove much, if not all, of the command latency associated with a write operation. Then ​​ write C ​​ obtains ​​ 01 ​​ and so on. SQL Server uses read-ahead logic to avoid query stalls caused by I/O waits.

Servers 40

Servers Cache Database Media 40

Smashing Magazine

AUGUST 9, 2021

You’ve probably heard things like: “HTTP/3 is much faster than HTTP/2 when there is packet loss”, or “HTTP/3 connections have less latency and take less time to set up”, and probably “HTTP/3 can send data more quickly and can send more resources in parallel”. HTTP/2 versus HTTP/3 protocol stack comparison ( Large preview ).

Transportation 145

Transportation Internet Internet Network 145

Smashing Magazine

SEPTEMBER 6, 2021

Finally, not inlining resources has an added latency cost because the file needs to be requested. If you do any comparison of this sort yourself (or if you read articles that do), make 100% sure that you’ve checked what’s actually going on. In our own early tests , I found seriously diminishing returns at about 40 files.

Network 104

Network Servers Cache Traffic 104