ld.so.cache and libc.so.6 memory-mapped for every call?
Playing with strace, it appears to me that ld.so.cache and libc.so.6 are opened and mapped to memory for almost every process. At least those processes that I experimented with. Doesn't this mean that these processes are mapped into process memory many many many times?
Sure, these files are pretty small, but isn't that a little wasteful of memory?
The strace output shows that these are being mmap'ed with MAP_PRIVATE set, which makes it copy-on-write, but there still appears to be a new mapping for every process.
My questions:
- Have I properly understood what is happening? That is, is there really a new copy of these files mapped into memory on every process that needs them (which appears to be every single one)?
- Is there some type of memory-sharing going on? That is, since the mapping is copy-on-write, are lots of processes looking at the same physical memory locations?
glibc strace mmap
asked 1 hour ago
smolloy
62
New contributor
smolloy is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
Playing with strace, it appears to me that ld.so.cache and libc.so.6 are opened and mapped to memory for almost every process. At least those processes that I experimented with. Doesn't this mean that these processes are mapped into process memory many many many times?
Sure, these files are pretty small, but isn't that a little wasteful of memory?
The strace output shows that these are being mmap'ed with MAP_PRIVATE set, which makes it copy-on-write, but there still appears to be a new mapping for every process.
My questions:
- Have I properly understood what is happening? That is, is there really a new copy of these files mapped into memory on every process that needs them (which appears to be every single one)?
- Is there some type of memory-sharing going on? That is, since the mapping is copy-on-write, are lots of processes looking at the same physical memory locations?
glibc strace mmap
asked 1 hour ago
smolloy
62
New contributor
smolloy is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
Playing with strace, it appears to me that ld.so.cache and libc.so.6 are opened and mapped to memory for almost every process. At least those processes that I experimented with. Doesn't this mean that these processes are mapped into process memory many many many times?
Sure, these files are pretty small, but isn't that a little wasteful of memory?
The strace output shows that these are being mmap'ed with MAP_PRIVATE set, which makes it copy-on-write, but there still appears to be a new mapping for every process.
My questions:
- Have I properly understood what is happening? That is, is there really a new copy of these files mapped into memory on every process that needs them (which appears to be every single one)?
- Is there some type of memory-sharing going on? That is, since the mapping is copy-on-write, are lots of processes looking at the same physical memory locations?
glibc strace mmap
asked 1 hour ago
smolloy
62
New contributor
smolloy is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Playing with strace, it appears to me that ld.so.cache and libc.so.6 are opened and mapped to memory for almost every process. At least those processes that I experimented with. Doesn't this mean that these processes are mapped into process memory many many many times?
Sure, these files are pretty small, but isn't that a little wasteful of memory?
The strace output shows that these are being mmap'ed with MAP_PRIVATE set, which makes it copy-on-write, but there still appears to be a new mapping for every process.
My questions:
- Have I properly understood what is happening? That is, is there really a new copy of these files mapped into memory on every process that needs them (which appears to be every single one)?
- Is there some type of memory-sharing going on? That is, since the mapping is copy-on-write, are lots of processes looking at the same physical memory locations?
glibc strace mmap
glibc strace mmap
asked 1 hour ago
smolloy
62
New contributor
smolloy is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 1 hour ago
smolloy
62
New contributor
smolloy is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 1 hour ago
smolloy
62
New contributor
smolloy is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 1 hour ago
smolloy
62
asked 1 hour ago
smolloy
62
62
New contributor
smolloy is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
smolloy is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
smolloy is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
Yes, every process gets its own mapping of the libraries it needs.
Yes, most of the data is shared, so every process “sees” the same physical memory (at different linear addresses), assuming the same version of each file is shared.
answered 54 mins ago
Stephen Kitt
163k24364444
add a comment |
Your Answer
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "106"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: false,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
smolloy is a new contributor. Be nice, and check out our Code of Conduct.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2funix.stackexchange.com%2fquestions%2f491142%2fld-so-cache-and-libc-so-6-memory-mapped-for-every-call%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
Yes, every process gets its own mapping of the libraries it needs.
Yes, most of the data is shared, so every process “sees” the same physical memory (at different linear addresses), assuming the same version of each file is shared.
answered 54 mins ago
Stephen Kitt
163k24364444
add a comment |
Yes, every process gets its own mapping of the libraries it needs.
Yes, most of the data is shared, so every process “sees” the same physical memory (at different linear addresses), assuming the same version of each file is shared.
answered 54 mins ago
Stephen Kitt
163k24364444
add a comment |
Yes, every process gets its own mapping of the libraries it needs.
Yes, most of the data is shared, so every process “sees” the same physical memory (at different linear addresses), assuming the same version of each file is shared.
answered 54 mins ago
Stephen Kitt
163k24364444
Yes, every process gets its own mapping of the libraries it needs.
Yes, most of the data is shared, so every process “sees” the same physical memory (at different linear addresses), assuming the same version of each file is shared.
answered 54 mins ago
Stephen Kitt
163k24364444
answered 54 mins ago
Stephen Kitt
163k24364444
answered 54 mins ago
Stephen Kitt
163k24364444
answered 54 mins ago
Stephen Kitt
163k24364444
163k24364444
add a comment |
add a comment |
smolloy is a new contributor. Be nice, and check out our Code of Conduct.
smolloy is a new contributor. Be nice, and check out our Code of Conduct.
smolloy is a new contributor. Be nice, and check out our Code of Conduct.
smolloy is a new contributor. Be nice, and check out our Code of Conduct.
Thanks for contributing an answer to Unix & Linux Stack Exchange!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Some of your past answers have not been well-received, and you're in danger of being blocked from answering.
Please pay close attention to the following guidance:
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2funix.stackexchange.com%2fquestions%2f491142%2fld-so-cache-and-libc-so-6-memory-mapped-for-every-call%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
