Errata

"Linux web servers" should be "Linux NFS servers" as this is the NFS subsection, web servers haven't been discussed yet, and if it's not "Linux NFS servers" that would mean Linux NFS servers were never mentioned in the whole book (and thus inconsistent with the other subsections in "Instant Tuning").

"for analyzing an applications' performance": either the singular "an" should be eliminated to match plural-possessive "applications'", or "applications'" should be changed to "application's" (singular).

"where we first starting comparing"
should be "start" or "started".

"changing an multi-threaded application's"
should be:
"changing a multi-threaded application's"

"the uplink from the switch from the server": one of those "from"'s should be a "to".

"If there is an insufficient amount of data, the application will be put to sleep."

Shouldn't the word "data" be "free socket buffer space"? If it really was "data", why would you put the application to sleep, from whence it cannot produce further data? If that were the case, wouldn't a packet never get sent?

Note from the Author or Editor:
"Data" should be replaced here with "free space in the socket buffer"

"until the RST segment is set"
shouldn't that be
"until the RST segment is sent"? Or something else? "set" doesn't really make sense here.

Note from the Author or Editor:
Strike "the RST segment is set and" from this sentence.

The "interface interface" line is confusing as both words are in the same typeface. This is a bit against convention used in the rest of the book, where you normally use a sample interface name. As per the book conventions as outlined on page xii, that typeface should only be used for "commands typed verbatim". A similar problem exists for the speed and duplex lines but in this case it is a bit clearer since most readers understand | to mean "or".

Note from the Author or Editor:
Please italicize the second "interface," "10|100|auto", and "half|full|auto."

The command says port "4/3" but the sample output says port "2/1", they should both be "4/3" like the example immediately prior on the previous page.

"This type of propagation..."

The "this" has not been defined, and is ambiguous. It is many sentences ago that the two types of propagation were mentioned, and both were mentioned equally fleetingly, so it is very unclear (at this point) what "this type" is. Perhaps "this" should be changed to "one".

Note from the Author or Editor:
Replace "This type of propagation" with "Another type of propagation"

"This set of rules is called a media access control, or MAC."
shouldn't this be:
"This set of rules is called a media access control, or MAC, protocol."

"Media access control" is almost always used as an adjective, not a noun. You could possibly use the original sentence if you drop the word "a", though I'm not really sure MAC is a "set of rules", as it really is the (MAC) protocol that defines the rules, not the MAC itself.

"RAID-5" is used here, but everywhere else in the book RAID levels are referenced without the dash, like "RAID 5". For consistency, this instance should be also.

"which is not good if you intended to boot from disk."

Perhaps the sentence ending should read "... from the RAID array".

"is written from a RAID 4 array", the array type should be 5, not 4.

I can't see how "2 (n-1)/n reads" is arrived at for degraded reads of "a single disk", nor the "n reads" for non-degraded reads. As per earlier in the paragraph, wouldn't a non-degraded single disk read (i.e., a tiny read that doesn't span disks in the stripe) be just 1 read? And degraded would be simply n-1? As it stands, the former equation gives 1.33 "reads" for n=3, which doesn't even make sense (must be a whole number?).

Note from the Author or Editor:
Here, the language is unclear and the equations misleadingly incorrect. This sentence should read: "When a RAID 5 array is running in a degraded state, a read operation to the failed device will incur (n - 1) individual disk reads, rather than just one."

For RAID 0 it says "each disk's utilization decreases by about 1/N". I'm confused on this point. It's also made on page 190 2nd-last paragraph, last sentence, about RAID 1: "disk utilization for an N-way mirror is reduced by 1/N." In both cases it is referring to random access (reads+writes for RAID 0 but reads-only for RAID 1).

I assume you mean an individual disk's utilization, not overall array disk utilization. I also assume you mean I/O utilization (not capacity, which isn't really being discussed around the text in question). In both cases, wouldn't an individual disk's utilization be reduced *to* 1/N, not *by* 1/N? If it reduced by 1/N that would mean as you increase disks to the array you increase each member disks' utilization (and lose performance, as per last sentence in the paw prints paragraph). That makes no sense to me. So perhaps the word "by" in both cases needs to be replaced by the word "to"? And perhaps "utilization" needs to be better defined?

Note from the Author or Editor:
"each disk’s utilization decreases by" should be replaced with "each disk's share of the workload decreases to"

Very awkward wording:
"... given that there are limitations for no operating system, SCSI host adapters, ..."

Maybe move the word "no" to before "limitations".

26.102 should be 26.101, to match example 5-3 from which it is taken. In the text paragraph below the table, the 9.074ms result is correct, as it is based on 26.101, not 26.102.

"... enabling the facility in production kernels wasn't generally done because it provided only a small performance overhead. IBM decided to leave the kernel tracing facility enabled..."

The "because" clause does not support the prior premise; indeed, it supports the following sentence instead. Perhaps an editing mistake? Changing the location of the period and changing "provided" to "required" is all that is required to fix it:

"... enabling the facility in production kernels wasn't generally done. Because it required only a small performance overhead, IBM decided to leave the kernel tracing facility enabled..."

Note from the Author or Editor:
Replace "because it provided only" with "because it imposed only"

From sentence 1 (along with paragraph 5 sentence 1), it sounds like the DNLC operates at the vnode level. But sentence 2 says "the DNLC figures out the right inode from the filename given". Is that technically valid, and if so, could some explanation be added as to the interplay between inode/vnode in the DNLC? If it is simply a typo, change the text from "inode" to "vnode".

Note from the Author or Editor:
"figures out the right inode" should read "figures out the right vnode"

"...are stored, etc.) Systems V systems..."
should be:
"...are stored, etc.). Systems V systems..."
or with "new, open" rules:
"...are stored, etc). Systems V systems..."

In any case, a period after the parenthesis is mandatory. Probably another amok automated editor looking for double-periods, since the author has not yet (as of p181) made this mistake elsewhere.

"underlying filesystem time" -> "underlying filesystem type"

"a sequential reads the extent, then all of the data."
should probably be:
"a sequential read reads the extent, then all of the data."

(Probably an automated double-word editing program gone amok.)

"the sevice times" -> "the service times"

"fibre" is not capitalized. All the other type names in the table are (and "fibre" is certainly its own type as there is no such thing as "Copper fibre").

"... the negotiated synchronous transfer speed to the device was configured as target 0; attached to this controller, it is 0x00002710 KB/second."

Nonsense as written. The speed can't be "target 0". Perhaps it was edited incorrectly. How about:

"... the negotiated synchronous transfer speed to the device (configured as target 0 on this controller) is 0x00002710 KB/second."

"provides a summary of the IDE implementations and the features it supports."

Subject is plural, so "it supports" must be changed to "each supports" or "they support", or similar wording.

"and the requesting data is in the drive's buffer"
should be:
"and the requested data is in the drive's buffer"

"Data ... is periodically written to data by fsflush..."

The 2nd "data" should probably be "disk".

"This minimizes the seek time to the disk"

Awkward wording. You don't really seek "to the disk". If by "disk" you mean a specific bit of rust (a sector, say) then it works: "This minimizes the seek time to the sector." But that doesn't make much sense given the context. I would guess it should have been "of the disk" (if "seek time" is meant to be the aggregate/plural), but it still might need the qualifier "average" before "seek time". Perhaps a complete revamp of the sentence would produce better results.

Note from the Author or Editor:
"This minimizes the seek time to the disk" should be replaced with "This minimizes seek time."

Two related problems:

1. lotsfree and desfree reference "freemem/high" and "freemem/low" respectively: the nomenclature is incorrect; the correct names are freepages.high and freepages.low as shown both later in the table and in the preceding text.

2. desfree says it's "roughly equivalent" to (corrected as per above) freepages.low, but freepages.low's entry says it's equivalent to minfree (not desfree). The minfree entry says "there is no equivalent parameter under Linux". The Solaris entry equivalencies need to jive with the Linux ones in a better manner. (Admittedly there is no perfect mapping; my best guess is minfree is roughly freepages.low, and desfree has no equivalent.)

Note from the Author or Editor:
1. Please correct #1 as per the reported errata.
2. freepages.low should be considered equivalent to desfree.

"The virtual memory system is responsible for managing the associations between the used portions of this virtual address space into physical memory".

"Between" requires two subjects: it's relational. Sounds like an edit error, and was probably originally the correct: "managing the mapping of the used portions". To keep the word "between", you could change "into" to "and".

"spins on mutexes; (in practical ... the first try)."

Semicolon before parentheses followed by period. Semicolon should be removed to follow English grammar/punctuation rules (the sentence should stand on its own with the entire parenthesized text removed, leaving ";." together, which obviously is incorrect).

"There are point-to-point connections between data path and devices connected to it"

almost certainly needs a "the" before "data path", or some other rewording.

Note from the Author or Editor:
Correct to read "...between the data path and all connected devices, which simplifies the arbitration logic."

Figure description text says "as a function ot L1 cache hit rate", but in-figure legend X-axis says "L2 cache hit rate". Both should be the same level, L1 or L2, I'm guessing.

Note from the Author or Editor:
Correct Figure 3-4 descriptive text to read "as a function of L2 cache hit rate."

"If automobile performance followed the same growth curve as microprocessors over the last 20 years, the successor to the DeLorean DMC-12 (1981-1983), which had a top speed of perhaps 140 miles per hour, would have doubled 12 times..."

Rewording required: the predicate "would have doubled 12 times" does not match the subject "the successor to the DeLorean DMC-12". The above boils down to: "the successor to the DeLorean DMC-12 would have doubled 12 times." Doubled what? Of course the context makes it clear the answer to that is "speed", but taken alone the sentence hints at other things, like weight, or size. Simply inserting "in speed" after "doubled" would suffice.

"illustrated in Table 2-4"
should be:
"illustrated in Table 2-5"
as it is 2-5 that shows the class distribution, whilst 2-4 shows the transaction type distribution.

"An payload-free packet"
should be:
"A payload-free packet"

The text reads:

"... we are limited to 64 (2^8) addresses in memory."

It should be 256 instead of 64, as 2^8 = 256.

And some lines below:

"... is about 16 petabytes (16777216 GB)"

2^64 bytes = 16 exabytes = 16384 petabytes = 16777216 terabytes

Note from the Author or Editor:
1. Please correct to "...we are limited to 256 (2^8) addresses..."
2. Please correct to "...16 exabytes (16777216 TB)"

messages a hour
should be:
messages per hour

It says "It's probably safe to assume that a 5-MIPS CPU will outperform a 100 MIPS
CPU, ...".
Clearly it had to be a 100 MIPS CPU outperforming a 5 MIPS CPU.

The fourth paragraph states that "The next four sections look at different process
scheduling models". However, there are only two sections covering process scheduling
models ("The System V Model: The Linux Model"; and "Multilayered Scheduling Classes:
The Solaris Model") before getting into "Multiprocessing".

The command output lists the following:

swapfile dev swaplo blocks free
... ... ... 788384 ...

Paragraph 6 refers to the number of blocks as "688384" instead of "788384."

First sentence: "from binary to hexadecimal." should read "from decimal to
hexadecimal"

For example 524569 decimal is 80119 hex.

Note from the Author or Editor:
Description of error is correct.

"It is by far the most common arithmatic optimization."

SHOULD BE:

"It is by far the most common arithmetic optimization."

Java Performance Tuning is written by Jack Shirazi and not by Jack Shiraz.