Feature #10187: minor iseq memory reductions

• Status: Closed
• Assignee: normalperson (Eric Wong)
• Target version: -

[normalperson (Eric Wong)]

Pretty trivial and low impact, but I figure we might as well reduce
memory footprint a few kilobytes where we can and let the reductions
accumulate. Feature #10185 has much bigger impact.

• [PATCH 1/2] iseq_inline_storage_entry: 24=>16 bytes on x86-64

We may tag the running_thread pointer to avoid making the "once" struct
bigger than "struct iseq_inline_cache_entry".

This only saves a small amount with "valgrind ruby -e exit"
before:
total heap usage: 48,122 allocs, 19,248 frees, 8,110,149 bytes allocated
after:
total heap usage: 48,122 allocs, 19,253 frees, 8,099,197 bytes allocated

• [PATCH 2/2] rb_call_info_t: 104=>96 bytes on x86-64

This keeps ci->flag and ci->aux.index consistent across 32-bit
and 64-bit platforms.

ci->flag: VM_CALL_* flags only use 9 bits, currently
ci->aux.index: 2 billion ivars per class should be enough for anybody

This saves around 50K allocations on "valgrind ruby -e exit"
before:
total heap usage: 48,122 allocs, 19,253 frees, 8,099,197 bytes allocated
after:
total heap usage: 48,069 allocs, 19,214 frees, 8,047,266 bytes allocated

[normalperson (Eric Wong)]

• File call_info-96.patch call_info-96.patch added

Missed patch 2/2

[normalperson (Eric Wong)]

• File call_info-96-v2.patch call_info-96-v2.patch added

updated 2/2 patch to adjust for r47456 (redundant SYM2ID <=> ID2SYM removal)

[ko1 (Koichi Sasada)]

Subject: [PATCH] iseq_inline_storage_entry: 24=>16 bytes on x86-64

+#define RUNNING_THREAD_ONCE_DONE ((rb_thread_t *)(0x1))

How about to define macro such as

#define ONCE_FINISHED(once) ((once)->running_thread == 0x01)

and use as

if (ONCE_FINIHSED(&is->once)) { ... }

Subject: [PATCHv2] rb_call_info_t: shrink to 96 bytes from 104 bytes on 64-bit

OK.

[ko1 (Koichi Sasada)]

+                if (newsize > INT_MAX) rb_memerror();

memerror?

[normalperson (Eric Wong)]

[e-mail] wrote:

Subject: [PATCH] iseq_inline_storage_entry: 24=>16 bytes on x86-64

+#define RUNNING_THREAD_ONCE_DONE ((rb_thread_t *)(0x1))

How about to define macro such as

#define ONCE_FINISHED(once) ((once)->running_thread == 0x01)

and use as

if (ONCE_FINIHSED(&is->once)) { ... }

I would need another macro for setting 0x1:

+	is->once.running_thread = RUNNING_THREAD_ONCE_DONE; /* success */

I prefer to only introduce one new macro.

[normalperson (Eric Wong)]

[e-mail] wrote:

•            if (newsize > INT_MAX) rb_memerror();
  

memerror?

I took the hint from compile_data_alloc:

    if (size >= INT_MAX) rb_memerror();
    if (storage->pos + size > storage->size) {
	unsigned int alloc_size = storage->size;

	while (alloc_size < size) {
	    if (alloc_size >= INT_MAX / 2) rb_memerror();
	    alloc_size *= 2;

Nobody hits the limit, so reusing rb_memerror keeps code size down.

[ko1 (Koichi Sasada)]

Eric Wong wrote:

Nobody hits the limit, so reusing rb_memerror keeps code size down.

how about to use rb_fatal() to declare give up?

[normalperson (Eric Wong)]

[e-mail] wrote:

Eric Wong wrote:

Nobody hits the limit, so reusing rb_memerror keeps code size down.

how about to use rb_fatal() to declare give up?

Actually, nobody hits that check anymore, I removed it.
Correct check is in r47512, thanks nobu!

[naruse (Yui NARUSE)]

• Target version deleted (2.2.0)

[normalperson (Eric Wong)]

• Status changed from Open to Closed