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* Added a simple mechanism to wait for events to VMCache. WaitForPageEvents()

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waits for certain events on a given page, NotifyPageEvents() wakes up
  waiting threads respectively.
* Used the new feature instead of condition variables for waiting on busy
  pages. We save publishing and unpublishing of a condition variable whenever
  a page is marked busy. There's only something to do, if there's at least
  one thread waiting in the list of the respective cache. The general
  assumption is that this is only rarely the case and even if it happens,
  there should be only very few threads.
* Added an apparently missing notification in cache_io(). At least I didn't
  see the reason for it not being there.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@34537 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Ingo Weinhold
2009-12-07 15:42:08 +00:00
parent 6440406a59
commit 522c2f19d4
5 changed files with 101 additions and 50 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/system/kernel/cache/file_cache.cpp
Vendored
+9 -23
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@@ -114,7 +114,6 @@ PrecacheIO::PrecacheIO(file_cache_ref* ref, off_t offset, size_t size)
fRef(ref),
fCache(ref->cache),
fPages(NULL),
fBusyConditions(NULL),
fVecs(NULL),
fOffset(offset),
fVecCount(0),
@@ -128,7 +127,6 @@ PrecacheIO::PrecacheIO(file_cache_ref* ref, off_t offset, size_t size)
PrecacheIO::~PrecacheIO()
{
delete[] fPages;
delete[] fBusyConditions;
delete[] fVecs;
fCache->ReleaseRefLocked();
}
@@ -144,10 +142,6 @@ PrecacheIO::Prepare()
if (fPages == NULL)
return B_NO_MEMORY;
fBusyConditions = new(std::nothrow) ConditionVariable[fPageCount];
if (fBusyConditions == NULL)
return B_NO_MEMORY;
fVecs = new(std::nothrow) iovec[fPageCount];
if (fVecs == NULL)
return B_NO_MEMORY;
@@ -159,7 +153,6 @@ PrecacheIO::Prepare()
if (page == NULL)
break;
fBusyConditions[i].Publish(page, "page");
fCache->InsertPage(page, fOffset + pos);
add_to_iovec(fVecs, fVecCount, fPageCount,
@@ -170,7 +163,7 @@ PrecacheIO::Prepare()
if (i != fPageCount) {
// allocating pages failed
while (i-- > 0) {
fBusyConditions[i].Unpublish();
fCache->NotifyPageEvents(fPages[i], PAGE_EVENT_NOT_BUSY);
fCache->RemovePage(fPages[i]);
vm_page_set_state(fPages[i], PAGE_STATE_FREE);
}
@@ -215,12 +208,12 @@ PrecacheIO::IOFinished(status_t status, bool partialTransfer,
}
fPages[i]->state = PAGE_STATE_ACTIVE;
fBusyConditions[i].Unpublish();
fCache->NotifyPageEvents(fPages[i], PAGE_EVENT_NOT_BUSY);
}
// Free pages after failed I/O
for (uint32 i = pagesTransferred; i < fPageCount; i++) {
fBusyConditions[i].Unpublish();
fCache->NotifyPageEvents(fPages[i], PAGE_EVENT_NOT_BUSY);
fCache->RemovePage(fPages[i]);
vm_page_set_state(fPages[i], PAGE_STATE_FREE);
}
@@ -383,7 +376,6 @@ read_into_cache(file_cache_ref* ref, void* cookie, off_t offset,
size_t numBytes = PAGE_ALIGN(pageOffset + bufferSize);
vm_page* pages[MAX_IO_VECS];
ConditionVariable busyConditions[MAX_IO_VECS];
int32 pageIndex = 0;
// allocate pages for the cache and mark them busy
@@ -393,8 +385,6 @@ read_into_cache(file_cache_ref* ref, void* cookie, off_t offset,
if (page == NULL)
panic("no more pages!");
busyConditions[pageIndex - 1].Publish(page, "page");
cache->InsertPage(page, offset + pos);
add_to_iovec(vecs, vecCount, MAX_IO_VECS,
@@ -417,7 +407,7 @@ read_into_cache(file_cache_ref* ref, void* cookie, off_t offset,
cache->Lock();
for (int32 i = 0; i < pageIndex; i++) {
busyConditions[i].Unpublish();
cache->NotifyPageEvents(pages[i], PAGE_EVENT_NOT_BUSY);
cache->RemovePage(pages[i]);
vm_page_set_state(pages[i], PAGE_STATE_FREE);
}
@@ -448,7 +438,7 @@ read_into_cache(file_cache_ref* ref, void* cookie, off_t offset,
for (int32 i = pageIndex; i-- > 0;) {
pages[i]->state = PAGE_STATE_ACTIVE;
busyConditions[i].Unpublish();
cache->NotifyPageEvents(pages[i], PAGE_EVENT_NOT_BUSY);
}
return B_OK;
@@ -504,7 +494,6 @@ write_to_cache(file_cache_ref* ref, void* cookie, off_t offset,
vm_page* pages[MAX_IO_VECS];
int32 pageIndex = 0;
status_t status = B_OK;
ConditionVariable busyConditions[MAX_IO_VECS];
// ToDo: this should be settable somewhere
bool writeThrough = false;
@@ -518,7 +507,6 @@ write_to_cache(file_cache_ref* ref, void* cookie, off_t offset,
// in cache_io()
vm_page* page = pages[pageIndex++] = vm_page_allocate_page(
PAGE_STATE_FREE, true);
busyConditions[pageIndex - 1].Publish(page, "page");
ref->cache->InsertPage(page, offset + pos);
@@ -616,7 +604,7 @@ write_to_cache(file_cache_ref* ref, void* cookie, off_t offset,
// make the pages accessible in the cache
for (int32 i = pageIndex; i-- > 0;) {
busyConditions[i].Unpublish();
ref->cache->NotifyPageEvents(pages[i], PAGE_EVENT_NOT_BUSY);
if (writeThrough)
pages[i]->state = PAGE_STATE_ACTIVE;
@@ -796,11 +784,7 @@ cache_io(void* _cacheRef, void* cookie, off_t offset, addr_t buffer,
return status;
if (page->state == PAGE_STATE_BUSY) {
ConditionVariableEntry entry;
entry.Add(page);
locker.Unlock();
entry.Wait();
locker.Lock();
cache->WaitForPageEvents(page, PAGE_EVENT_NOT_BUSY, true);
continue;
}
}
@@ -845,6 +829,8 @@ cache_io(void* _cacheRef, void* cookie, off_t offset, addr_t buffer,
page->state = oldPageState;
if (doWrite && page->state != PAGE_STATE_MODIFIED)
vm_page_set_state(page, PAGE_STATE_MODIFIED);
cache->NotifyPageEvents(page, PAGE_EVENT_NOT_BUSY);
}
if (bytesLeft <= bytesInPage) {